Gr 11-Agricultural Sciences-Study Guide

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AGRICULTURAL SCIENCES STUDY GUIDE Grade 11

A member of the FUTURELEARN group

Agricultural Sciences Study guide

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Í3+È-E-AGS-SG01hÎ

Grade 11

CAPS aligned

All photos provided by AFGRI

M Kotzè JC Zandberg

Study Guide G11 ~ Agricultural Sciences

CONTENTS INTRODUCTION............................................................................................................................................... 13 ADDITIONAL SOURCES................................................................................................................................. 13 RESOURCES.................................................................................................................................................... 13 LESSON ELEMENTS....................................................................................................................................... 14 TIMETABLE AND TIME MANAGEMENT........................................................................................................ 15 ASSESSMENT REQUIREMENTS................................................................................................................... 16 STUDY TIPS AND METHODS.......................................................................................................................... 17 YEAR PLAN...................................................................................................................................................... 18 UNIT 1: BASIC AGRICULTURAL CHEMISTRY............................................................ 20 Lesson 1: Introduction to chemistry.............................................................................. 21 1. Important terminology................................................................................................ 22 2. Differences between: Elements, Compounds and Mixtures....................................... 30 3. The basic interpretation of the Periodic Table of elements......................................... 31 4. The difference between acids and bases................................................................... 34 5. The general structure of an atom............................................................................... 38 6. Types of atom particles and charges.......................................................................... 38 7. Relation between atomic numbers and number of particles in the nucleus................ 39 8. Formation of ions....................................................................................................... 40 9. Arrangement of electrons around the nucleus and valence....................................... 42 Summary........................................................................................................... 46 Test yourself 1................................................................................................... 48 Lesson 2: Chemical bonding........................................................................................... 51 1. Basic chemical bonding as it occurs to form a molecule............................................ 51 2. Chemical bonding and structural formulae................................................................. 52 Summary........................................................................................................... 61 Test yourself 2................................................................................................... 63 Lesson 3: Inorganic and organic compounds............................................................... 64 1. The distinction between inorganic and organic compounds....................................... 65 2. Chemical formulae, structures and functions of inorganic compounds...................... 66 3. The characteristics of the carbon atom (bonding on the carbon atom) and organic substances................................................................................................................. 73 4. The basic grouping of organic compounds................................................................. 74 Summary........................................................................................................... 77 Test yourself 3................................................................................................... 78 Lesson 4: Alkanes and alcohols..................................................................................... 79 1. The basic types of alkanes......................................................................................... 81 2. Chemical and structural formulae of alkanes............................................................. 81 3. Importance of alkanes in plants and animal metabolism............................................ 83 4. The concept: isomers as illustrated by simple alkane structures................................ 84 5. The basic types of alcohols, their structures and importance.................................... 86

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Study Guide G11 ~ Agricultural Sciences

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Comparisons between alcohols and alkanes based on their general structural formulae..................................................................................................................... 87 Summary........................................................................................................... 89 Test yourself 4................................................................................................... 90 Lesson 5: Fatty acids, bio-molecules and lipids/fats................................................... 91 1. The chemical structure of a simple fatty acid............................................................. 92 2. Saturated and unsaturated fatty acids........................................................................ 93 3. The differences between fatty acids and alcohols...................................................... 96 4. Basic composition of a simple lipid/fat........................................................................ 98 5. The differences between fats and oils, saturated and unsaturated fats.................... 102 6. The main functions and importance of lipids/fats in living organisms....................... 103 Summary......................................................................................................... 103 Test yourself 5................................................................................................. 104 Lesson 6: Proteins......................................................................................................... 105 1. General structure of the monomers of proteins (amino acids).................................. 106 2. The difference between simple and complex proteins.............................................. 108 3. General structure of a polypeptide/simple proteins.................................................. 109 4. The synthesis and hydrolysis of proteins.................................................................. 109 5. The main functions/importance of proteins in living organisms................................. 111 Test yourself 6................................................................................................. 112 Lesson 7: Carbohydrates.............................................................................................. 112 1. The basic chemical composition of carbohydrates....................................................114 2. The general formulae of carbohydrates.....................................................................114 3. Structural and chemical formulae of simple sugars (monosaccharides)....................114 4. The main classification of carbohydrates – monosaccharide, disaccharides and polysaccharides........................................................................................................117 5. The main functions of carbohydrates in living organisms......................................... 120 Summary ........................................................................................................ 121 Test yourself 7................................................................................................. 122 UNIT 2: SOIL SCIENCE................................................................................................... 123 Lesson 8: Soil texture.................................................................................................... 124 1. The concept: Soil texture......................................................................................... 125 2. The main groupings of soil particles (clay, silt and sand) that determine the soil textures and their respective diameters.................................................................... 125 3. Scientific method to determine the quantity of sand, silt and clay in a soil sample (use a sieve/mechanical/chemical method).............................................................. 126 4. Determination of the textural classes (soil texture triangle) of soil and interpretation of textural triangle..................................................................................................... 128 5. The influences of sand and clay particle size/texture on soil characteristics/ behaviour................................................................................................................. 129 6. The two field methods to determine the soil texture class: sausage method and feeling method.......................................................................................................... 130 Š Impaq

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Study Guide G11 ~ Agricultural Sciences

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The most important reasons for a farmer having to know the textural class of his farm land ..........................................................................................................................................131 Summary......................................................................................................... 132 Test yourself 8................................................................................................. 133 Lesson 9: Soil structure................................................................................................ 133 1. The concept: Soil structure...................................................................................... 135 2. The classification/types of soil structures (shape and size)...................................... 135 3. Factors influencing the development and stability of soil structure........................... 138 4. The factors or malpractices that cause destruction/decline in soil structure............. 139 5. The different methods that farmers can apply to improve a poor soil structure........ 140 6. The advantages of good soil structure .................................................................... 140 Test yourself 9................................................................................................. 143 Lesson 10: Soil colour and soil pores.......................................................................... 143 1. The differences between homogeneous and non-homogeneous soil colour........... 145 2. The main factors that determine the colour of soil.................................................... 145 3. The interpretation of the following soil colours...................................................... 146 4. The effect of soil texture, soil structure, soil depth and soil cultivation on the total pore space in a soil.................................................................................................. 148 5. The difference between macro pores and micro pores and their functions in a soil.149 6. Bulk density and porosity......................................................................................... 150 7. Ways to determine, calculate and interpret the bulk density of soil...........................151 8. Factors that influence the bulk density of soil........................................................... 152 Summary......................................................................................................... 153 Test yourself 10............................................................................................... 153 Lesson 11: Soil air.......................................................................................................... 153 1. The factors that affect/influence storage and movement of soil air.......................... 155 2. Comparison between atmospheric and soil air (based on nitrogen, oxygen and carbon dioxide content)........................................................................................... 155 3. The importance/necessity of the following soil gases: oxygen, carbon dioxide and nitrogen.................................................................................................................... 157 Summary......................................................................................................... 158 Test yourself 11................................................................................................ 159 Lesson 12: Soil moisture............................................................................................... 159 1. The basic types of soil water and their characteristics............................................. 161 2. A description of soil water losses and ways to limit their losses............................... 163 3. The forces of nature that have an effect on soil water (adsorption, electrostatic, capillarity, bonding, cohesion etc.)............................................................................ 166 4. The different movements of water through soil......................................................... 169 5. The availability of soil water to a plant at the following limits of soil water content....170 6. Scientific methods to illustrate the following aspects that are related to soil water... 172 7. Effective soil water management...............................................................................174 Test yourself 12............................................................................................... 176

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Lesson 13: Soil temperature......................................................................................... 176 1. The main factors influencing soil temperature.......................................................... 177 2. The scientific approach to measure the effect of these factors that influence soil temperature............................................................................................................. 180 3. The effects of soil temperature on physical, chemical and biological processes that take place in soil .................................................................................................... 182 4. The ways/methods to manipulate soil temperature for better production (cultivation methods and controlled environment)...................................................................... 183 Test yourself 13............................................................................................... 185 Lesson 14: Soil morphology......................................................................................... 185 1. The terminology: soil profile, soil horizon and soil profile hole................................. 186 2. The development and description of the master horizons........................................ 187 3. The soil profiles........................................................................................................ 189 4. A practical identification of topsoil and subsoil horizons........................................... 190 Test yourself 14............................................................................................... 192 Lesson 15: Soil classification....................................................................................... 192 1. Description of soil classification and the use of a binomial soil classification system in South Africa.......................................................................................................... 194 2. The procedures to be followed when identifying and classifying soil by the binomial system...................................................................................................................... 195 3. The reasons/purposes/value of the classification of soils in agriculture................... 197 4. The description of diagnostic horizons of the topsoil and subsoil horizons.............. 197 Test yourself 15............................................................................................... 200 Lesson 16: Soil colloids................................................................................................ 201 1. The description and characteristics of inorganic soil colloids................................... 202 2. The differences between inorganic and organic colloids, cation adsorption and cation exchange in soil............................................................................................. 204 3. Manipulation of the cations and cation exchange in the soil..................................... 207 4. The pH scale and hydrogen ions concentration........................................................211 5. The concepts: soil acidity (predominant cations) ......................................................211 6. The distinction between active acidity and reverse acidity........................................212 7. The factors influencing/causing the soil acidification process...................................213 8. The effects of soil acidity on crop production............................................................214 9. The methods of preventing/controlling soil acidification........................................... 215 10. The exchange reaction in the soil that occurs during the reclamation process (chemical reaction)................................................................................................... 215 Test yourself 16............................................................................................... 217 Lesson 17: Soil alkalinity and salinity.......................................................................... 217 1. The concept: soil alkalinity (predominant cations).................................................... 218 2. The differences between saline soils and sodic soils............................................... 220 3. The characteristics of saline soils and white brackish soils...................................... 220 4. The factors influencing/causing brackishness/soil alkalinity/saltiness...................... 221 5. The effects of alkaline/brackishness on crop productivity........................................ 221 Š Impaq

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Study Guide G11 ~ Agricultural Sciences

6. The methods of preventing/controlling soil alkalinity................................................. 222 7. The procedures to be followed on the reclamation of alkaline/brackish soils........... 222 Test yourself 17............................................................................................... 224 Lesson 18: Living organic matter................................................................................. 224 1. The difference between soil micro-organisms and macro-organisms (with examples)........................................................................................................ 225 2. The main groups of soil micro- and macro-organisms............................................. 227 3. The importance and roles of soil micro- and macro-organisms............................... 229 4. The requirements for soil micro- and macro-organisms........................................... 230 5. The carbon cycle/conversion by micro-organisms................................................... 230 6. The nitrogen cycle/conversion by micro-organisms................................................. 231 7. The process of symbiosis based on the following: mycorrhiza (fungus) and Rhizobium bacteria................................................................................................. 232 8. The terminology: ammonification, nitrification, denitrification, nitrogen, assimilation, solubilisation, immobilisation and mineralisation...................................................... 233 Test yourself 18............................................................................................... 235 Lesson 19: Non-living organic matter.......................................................................... 235 1. Definitions of the following concepts: fresh organic matter and humus.................... 236 2. The physical, chemical and biological effect of organic matter on soils................... 237 3. The factors affecting the balance between gains and losses of organic matter in soils.......................................................................................................................... 238 4. The effect of the decline in organic matter content on soil degradation ............. 240 Test yourself 19............................................................................................... 241 UNIT 3: PLANT STUDIES............................................................................................... 242 Lesson 20: Plant nutrition and photosynthesis.......................................................... 243 1. The schematic representation of photosynthesis..................................................... 244 2. The differences between photosynthesis and respiration......................................... 246 3. The main pigment involved in photosynthesis and its function in plants................... 246 4. The importance/role of photosynthesis .................................................................. 247 5. The dark and light reaction/phases of photosynthesis............................................ 248 6. The storage of food and various organs utilised for food storage in plants.............. 250 7. The factors influencing the rate of photosynthesis................................................... 251 8. The manipulation of plants to increase the photosynthetic rate................................ 252 Test yourself 20............................................................................................... 253 Lesson 21: Water and nutrients.................................................................................... 254 1. The importance/functions of water in plants............................................................. 255 2. The movement of water from the soil to the roots of the plants................................ 256 3. The distinctions between osmosis and diffusion...................................................... 257 4. The differences between the following processes: Movement of water from the roots to the stems and leaves, movement of water from the leaf to the air (atmosphere)............................................................................................................ 259

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Study Guide G11 ~ Agricultural Sciences

5. The terms: transpiration pull and osmotic flow......................................................... 261 6. Plants’ adaptation features to reduce transpiration rate (how plants control transpiration)............................................................................................................ 262 7. Movement of the products of photosynthesis (nutrients).......................................... 263 Test yourself 21............................................................................................... 264 Lesson 22: Mineral nutrition: Macro- and micro-elements......................................... 266 1. The differences between micro-/trace elements and macro-elements .................... 267 2. The different macro-elements: Nitrogen, sulphur, phosphorus, potassium, calcium and magnesium (importance/functions and form in which it is absorbed and the deficiency symptoms of each)...........................................................................268 3. The different micro-elements: Iron, manganese, boron, zinc, copper, molybdenum and cobalt (importance/functions and form in which it is absorbed and the deficiency symptoms of each)................................................................................................... 273 Test yourself 22............................................................................................... 277 Lesson 23: The plant nutrient uptake and analysis.................................................... 277 1. Plant nutrient/mineral uptake.................................................................................... 278 2. The forms in which nutrients/minerals are available to plants.................................. 279 3. The factors affecting/influencing nutrients/minerals such as phosphorus, potassium and nitrogen availability to plants............................................................................. 280 4. The importance of nutrient element analysis in crop production.............................. 283 5. Methods utilised in crop production to determine the nutritional status of soil (soil samples, plant/leaf samples)............................................................................. 283 Test yourself 23............................................................................................... 285 Lesson 24: Organic and inorganic fertilisers.............................................................. 286 1. A definition of the term ‘fertiliser’.............................................................................. 286 2. The difference between organic and inorganic fertilisers......................................... 287 3. The main nitrogenous, phosphorus and potassium inorganic fertilisers (their uses/ applications with relevant examples)........................................................................ 288 4. The calculation of the percentages of each plant nutrient in the fertiliser mixtures/ multi fertiliser mixtures............................................................................................. 291 5. Impact of inorganic fertilisers on the environment.................................................... 291 6. The differences between calcitic and dolomitic lime................................................. 292 7. The beneficial effect of liming (physical, chemical and biological effects)................ 293 8. The use of gypsum................................................................................................... 295 Test yourself 24............................................................................................... 295 Lesson 25: Organic fertilisers and fertilisation practices.......................................... 296 1. The main types of organic fertilisers........................................................................ 297 2. Impact of organic fertilisers...................................................................................... 298 3. The concept: green manure..................................................................................... 298 4. The purpose/beneficial effects of green manuring................................................... 299 5. The characteristics of green manure crops ............................................................. 300 6. The concept: farm manure....................................................................................... 300 7. The types of farm manure ....................................................................................... 300 © Impaq

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The factors that affect/influence the composition of farm manure............................ 300 The description of compost...................................................................................... 301 The preparation and requirements for compost production...................................... 302 The beneficial effects of compost (physical, chemical and biological effects) on plant growth.............................................................................................................. 303 12. The common agricultural organic products and by-products used to supplement plant nutrients........................................................................................................... 303 13. The different methods of fertiliser applications in relation to soil.............................. 304 Test yourself 25............................................................................................... 308 Lesson 26: Plant reproduction: sexual reproduction and pollination....................... 309 1. The definition of sexual reproduction in plants..........................................................311 2. The functions and structures of the following parts of a flower..................................311 3. The concept: pollination............................................................................................314 4. The differences between self-pollination and cross pollination..................................314 5. The description of the main agents of pollination......................................................316 Test yourself 26............................................................................................... 317 Lesson 27: Fertilisation and ablactation...................................................................... 318 1. What is fertilisation?..................................................................................................319 2. The structure of matured/ripe pollen grain and a receptive stigma............................319 3. The germination of a ripe pollen grain on a receptive stigma until fertilisation......... 320 4. The terminology: fertilisation and double fertilisation................................................ 321 5. The development of a fertilised ovule to form a seed/fruit (structural development).322 6. The distinction between vegetative and stimulative parthenorcarpy......................... 323 7. The concept: Ablactation.......................................................................................... 323 8. The factors causing/influencing ablactation............................................................. 324 9. The concept: fruit setting and germination............................................................... 325 10. The development of seeds/fruits from a fertilised flower (structures) ....................... 325 11. The different types of fruits according to the way in which they develop such as simple, compound, multiple and accessory fruits..................................................... 326 12. The process of seed germination............................................................................. 326 13. The distinction between seed dormancy and scarification....................................... 327 14. The basic requirements for seed germination.......................................................... 328 Test yourself 27............................................................................................... 329 Lesson 28: Asexual reproduction................................................................................. 330 1. The concept: asexual reproduction/vegetative reproduction in plants...................... 331 2. Types of asexual methods of reproduction/vegetative reproduction in plants (bulbs, tubers, cuttings, sprouts, rhizome)........................................................................... 332 3. Osculation and grafting............................................................................................ 334 4. The advantages and disadvantages of using asexual reproduction methods to propagate plants..................................................................................................... 336 Test yourself 28............................................................................................... 337 Lesson 29: Plant improvement and biotechnology.................................................... 338 1. Description of methods used in plant breeding: Selection, hybridisation

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Study Guide G11 ~ Agricultural Sciences

(hybrid seeds) and mutation................................................................................... 339 2. The use of gene mutation by plant breeders to improve plant production................ 344 3. The concept: Biotechnology..................................................................................... 344 4. The advantages and disadvantages of genetic modified crops/plants (GMOs)........ 344 5. The characteristics of GMOs.................................................................................... 345 6. Examples of genetically modified crops in South Africa, for example, maize (Bt-maize) and cotton (Bt-cotton), etc. ..................................................................... 345 Test yourself 29............................................................................................... 346 Lesson 30: Weed control management........................................................................ 347 1. Weeds and herbicides.............................................................................................. 348 2. The harmful effects of weeds on plant growth.......................................................... 348 3. The adaptation features/modes of weeds, which let them grow more easily than cultivated crops....................................................................................................... 350 4. The agents of weed dispersion/transmission from one field to another.................... 350 5. The description of the methods of weed control: mechanical, chemical, biological and integrated weed control management............................................................... 351 Test yourself 30............................................................................................... 353 Lesson 31: Plant diseases/pests and their control..................................................... 354 1. The types of micro-organisms causing diseases in plants....................................... 355 2. The various plant diseases caused by micro-organisms (mode of transmission, symptoms and affected plants)................................................................................. 355 3. The preventative/control measures of plant disease................................................ 358 4. The terminology: Pesticides..................................................................................... 359 5. The description of main groups of plant pests and life cycles of some of plant pests........................................................................................................................ 359 6. The types of damage caused by plant pest on crops............................................... 361 7. The preventative/control measures/methods of plant pests...................................... 362 8. The concept: Integrated pest management.............................................................. 363 9. The advantages/benefits of practising IPM by crop farmers.................................... 363 10. The fundamental principles/steps to be followed that determine IPM....................... 364 11. Insect control of stored seeds and grasses.............................................................. 364 12. The conditions, which influence/increases insect damages on stored seeds/ grains....................................................................................................................... 364 13. The life cycle of selected pests/insects of stored agricultural products.................... 364 14. The various methods of controlling insects in stored seeds/grain............................ 365 Test yourself 31............................................................................................... 366 UNIT 4: OPTIMAL RESOURCE UTILISATION............................................................... 368 Lesson 32: Soil surveying and planning...................................................................... 369 1. The concept: Soil survey.......................................................................................... 370 2. The purpose (aims and principles) of soil survey.......................................................371 3. The soil survey process in agriculture and steps, which need to be followed during soil surveying............................................................................................................371 Š Impaq

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Study Guide G11 ~ Agricultural Sciences

4. The concept: Precision farming................................................................................ 372 5. The basic principles/aims of precision farming......................................................... 373 6. The main ultra-modern technologies utilised with precision farming.........................374 Test yourself 32............................................................................................... 375 Lesson 33: Water use / irrigation.................................................................................. 376 1. The terminology: irrigation, irrigation schedule......................................................... 377 2. The main sources of water for irrigation .................................................................. 378 3. The criteria to determine water quality for irrigation (advantages and disadvantages, and conditions to use).............................................................................................. 378 4. The irrigation systems (advantages and disadvantages, and conditions to use)...... 379 5. The reasons or advantages of irrigation scheduling................................................. 382 6. The use of the following instruments to determine the moisture content of soils.......................................................................................................................... 382 Test yourself 33............................................................................................... 383 Lesson 34: Soil drainage systems, soil cultivation and crop rotation...................... 384 1. The term: Soil drainage............................................................................................ 385 2. Different types of soil drainage systems................................................................... 386 3. The critical areas, which should be considered before installation of a pipe drainage system in the field.................................................................................................... 387 4. The aims of primary and secondary soil cultivation.................................................. 388 5. Differentiation between primary and secondary soil cultivation................................ 388 6. Different types of common implements utilised for soil cultivation............................ 389 7. The description and comparison of different types of soil cultivation systems....... 393 8. The concept: Crop rotation....................................................................................... 395 9. The differences between monoculture and crop rotation......................................... 395 10. The factors which play a fundamental role when a farmer plans a crop rotation programme............................................................................................................... 396 11. The advantages and disadvantages of crop rotation................................................ 397 Test yourself 34............................................................................................... 398 Lesson 35: Greenhouse, hydroponics and aquaculture............................................ 398 1. The concept: Greenhouse........................................................................................ 399 2. The benefits/advantages and disadvantages of having a greenhouse for production of high-value cash crops.......................................................................................... 400 3. The types of material used by farmers to construct a greenhouse........................... 401 4. The environmental factors to be considered when selecting/choosing the general locality of the greenhouse........................................................................................ 401 5. The concept: Hydroponics production system.......................................................... 402 6. The advantages/benefits of hydroponics production systems.................................. 403 7. Growing mediums that will support plants which can be used by growers in hydroponics systems ............................................................................................... 404 8. The advantages and disadvantages of closed and open systems in hydroponic production ............................................................................................................... 406

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Study Guide G11 ~ Agricultural Sciences

9. The differences between production in a hydroponic system and open field open system........................................................................................................... 406 10. The concept: Aquaculture........................................................................................ 407 11. Common species, which are included in aquaculture farming in South Africa............................................................................................................ 408 12. The common and simple structures that can be used for housing both marine and fresh water species.................................................................................................. 408 13. The description of the fish culture systems: Open through flow system and closed or recirculation system............................................................................................. 409 14. The basic requirements for aquaculture farmers to achieve high yields....................409 15. The factors, which may restrict farmers from choosing certain species for aquaculture

farming......................................................................................................................410 Test yourself 35................................................................................................411 BIBLIOGRAPHY AND ACKNOWLEDGEMENTS.......................................................... 412 ADDENDUM A: Elements of the Periodic Table............................................................ 413 ADDENDUM B: Colour pages......................................................................................... 417

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Study Guide G11 ~ Agricultural Sciences

INTRODUCTION What does Agricultural Sciences involve?

Agricultural Sciences is the study of the relationship between soil, plants and animals in the production and processing of food, fibre, fuel and any other agricultural product, which has an economic, aesthetic and cultural value.

It is an integrated science, which combines the knowledge and skills of Physical Sciences, Life Sciences, Social Sciences, Soil Sciences, Engineering, Mathematics and Economics.

This subject must be seen within the holistic science framework and not as an isolated science. Agricultural Sciences embeds a sustainable agricultural environment by integrating theory and skills in the study of the food production chain and processing. It focuses on the management skills needed to sustain production in a viable way.

The main topics in the Agricultural Sciences curriculum are: 1.

Soil sciences 2.

Plant studies 3.

Animal studies 4.

Agricultural economics 5.

Basic agricultural chemistry 6.

Basic genetics and biological concepts 7.

Sustainable natural resource utilisation 8.

Agroecology

ADDITIONAL SOURCES Agricultural Sciences for All by W Burger: N Phewa; M Burger Focus on Agricultural Sciences by J de Fontaine; B Letty; K Morrison; A Smuts The New Agricultural Science by Burger; Moolman Agricultural magazines: Farmer’s Weekly, Agri Farmer and Stock Farm.

The internet.

RESOURCES You need the following resources to complete the subject successfully: • Impaq study guide • Impaq facilitator’s guide • Impaq portfolio book • June examination • November examination • Clothes, shoes and equipment needed for physical activities • A farm where practical work can be done

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Study Guide G11 ~ Agricultural Sciences

LESSON ELEMENTS

LEARNING AIMS

What the learner should know at the end of the lesson. Taken from CAPS.

IMPORTANT TERMINOLOGY

New terminology to extend understanding of the subject as part of the lesson.

DEFINE

Definitions of concepts to help the learner understand the content.

IMPORTANT

A summary or explanation of key concepts explained in the lesson.

TIPS

Information in addition to the content to guide the learner through the learning process.

FOR THE CURIOUS

Encouragement for the learner to do in-depth research about the content on his/her own.

CORE CONTENT

Reinforcement of core content; in-depth explanation of a specific section of the lesson.

ACTIVITY

Formative assessment to test the learner’s progress and knowledge of each completed lesson.

EXERCISE

Formative assessment to test the learner’s progress and knowledge of each completed unit.

STUDY/REVISION

Demarcation or summary of work to be revised in preparation for tests and examinations.

* All lesson elements are not necessarily used in this guide.

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Study Guide G11 ~ Agricultural Sciences

Every lesson will consist of the following learning activities: • A challenge • Agricultural Sciences content • Activities to solve the challenge • Application and revision As well as: • Learning outcomes • Definitions • Enrichment activities (For the curious) • Summaries • Self-assessment activities

TIMETABLE AND TIME MANAGEMENT The suggested time allocation for Agricultural Sciences in Grade 11: Number of units per year 4 units/year Total number of weeks available to study this content in Grade 11 30 Duration of each unit ± 7 weeks Number of units 4 Suggested time allocation per unit 4 hours/week Number of lessons per unit 7-10 lessons Duration per lesson 45 minutes * Try to work at least one hour per day. You may choose which four days a week to spend on Agricultural Sciences.

Requirements for Agricultural Sciences as subject: • • • • • • • • • •

Each learner should have a study guide.

Keep in mind that the learners also have to complete tasks in Agricultural Sciences and therefore have to allow enough time to work on those.

Learners must have access to a farm where the required practical assessment tasks can be done.

Review the previous day’s work daily.

Make use of the assignments in the study guide. Completing the assignments will help with preparation for the examination.

Assignments in the study guide do NOT form part of the portfolio work.

Portfolio work consists of the seven tasks as set in the assessment plan in the portfolio book and must be handed in separately – ONLY these tasks form part of the portfolio.

NO portfolio – NO marks. It is very important to keep the portfolio up-to-date and submit tasks or the marks according to the dates provided in the assessment plan in the portfolio book.

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Study Guide G11 ~ Agricultural Sciences

ASSESSMENT REQUIREMENTS Portfolio Marks Submission date Task 1 Practical assignment 50 See portfolio book Task 2 Term 1 test 75 See portfolio book Task 3 Practical investigation 50 See portfolio book Task 4 June examination 150 See portfolio book Task 5 Research project 50 See portfolio book Task 6 Term 3 test 75 See portfolio book Task 7.1 November examination 1 150 See portfolio book Task 7.2 November examination 2 150 See portfolio book * The assessment tasks contribute 25% to the final mark. * The work done in terms 1 and 2 are assessed in the June examination.

Format of November examination The June examination (only one paper) will have the same format, but not all the content since not all the content will have been covered yet.

The November examination (two papers) will consists of the following:

• •

Content Basic agricultural chemistry Soil sciences

PAPER 1 Duration: 2½ hours Section A Section B Question 1 Question 2 - 4 105 45 (35 marks per question)

PAPER 2 Duration: 2½ hours Content Section A Section B • Plant studies Question 1 Question 2 - 4 • Optimal resource 105 45 (35 marks per question) utilisation * The final examination marks are 300 – thus 75% of the total mark. * The SBA marks are 100 – thus 25% of the total mark.

Total marks = 100 + 300 = 400 ÷ 4 = 100

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Total 150

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Study Guide G11 ~ Agricultural Sciences

STUDY TIPS AND METHODS Agricultural Sciences is a science – therefore, learners taking this subject must spend a lot of time on intensive study to master all the facets and facts of the subject.

• Don’t let the work pile up and become too much – study on a daily basis.

• After completing a chapter, make sure you learn the facts and make summaries.

• Make sure you understand all the material and ask somebody to explain it if you do not.

• If you wait too long until you ask for an explanation, you may discover that the material does not make sense and you then need more time to learn the work.

• Make use of diagrams, redraw the sketches yourself and underline the important facts.

• Sketches in tests and examinations can differ from the study guide sketches.

• Use other text books or google different images for the same topic.

• Make columns of the difficult names – make sure that you know the meaning of each of those names.

• Use the activities in the study guide as tests – after completing a lesson, first study the material and complete the questions in the activity as you would do in a test – in this way, you will be able to see, which part of the work you haven’t mastered yet.

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Study Guide G11 ~ Agricultural Sciences

YEAR PLAN UNIT WEEK LESSON

LESSON CONTENT TERM 1

1

BASIC AGRICULTURAL CHEMISTRY 1 2 3 4 5 6 7

2

1 2 3 4 5 6 7

Introduction to chemistry Chemical bonding Inorganic and organic compounds Alkanes and alcohols Fatty acids, bio-molecules and lipids/fats Proteins Carbohydrates

SOIL SCIENCE 8 9 10

8 9 10

Soil texture Soil structure Soil colour and pores TERM 2

2

SOIL SCIENCE 11 12 13 14 15 16 17

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Soil air Soil moisture Soil temperature Soil morphology Soil classification Soil colloids and soil acidity Soil alkalinity and salinity

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TARGET DATE

Study Guide G11 ~ Agricultural Sciences

UNIT WEEK

Lesson

LESSON CONTENT

TARGET DATE

TERM 3 2

3

SOIL SCIENCE 18

18

19

19

Soil organic matter: Living organic matter Soil organic matter: Non-living organic matter

PLANT STUDIES 20 21

20 21

22

22

23 24 25

23 24 25

26

26

27

27

Plant nutrition and photosynthesis Water and nutrients Mineral nutrition: Macro- and micro-elements Plant nutrient uptake and analysis Organic and inorganic fertilisers Organic fertilisers and fertilisation practices Plant reproduction: Sexual reproduction and pollination Fertilisation and ablactation Seeds and fruit setting Seed germination TERM 4

3

PLANT STUDIES 28 29 30 31

4

28 29 30 31

Plant reproduction: Asexual reproduction Plant improvement and biotechnology Weed control management Plant diseases/pests and their control

OPTIMAL RESOURCE UTILISATION 32 32

32 33

33

34

34

35

Soil surveying and planning Water use and irrigation Soil drainage systems, cultivation and crop rotation Greenhouses, hydroponics and aquaculture

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Basic agricultural chemistry

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Study Guide G11 ~ Agricultural Sciences

Unit

1

Lesson 1: Introduction to chemistry LEARNING AIMS After completing this lesson, you must be able to: 1.

Define the following terminology: matter, atoms, molecules, periodic table, isotopes, elements, compounds and mixtures.

2.

Identify the differences between elements, compounds and mixtures (with relevant examples).

3.

Interpret the periodic table of elements 4.

Differentiate between acids and bases.

5.

Draw the general structure of an atom and know the different particles of an atom and their function.

6.

Identify the main types of particles of an atom and their respective charges.

7.

Give the relation between atomic numbers and number of particles in the nucleus.

8.

Identify the formation of ions.

9.

Give the arrangement of electrons around the nucleus and the valence.

Adapted from Parker & Hart, Wizard of Id

Agricultural chemists may work with the Department of Agriculture, the Environmental Protection Agency, the Food and Drug Administration or for private industry.

Agricultural chemists develop fertilisers, insecticides and herbicides necessary for large-scale crop production. They must also monitor how these products are used and their impacts on the environment. Nutritional supplements are developed to increase the productivity of meat and dairy herds.

Chemistry is part of everything done in agriculture. Therefore it is of utmost importance to have a good understanding of agricultural chemistry.

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INTRODUCTION This section begins with chemical analysis in agriculture and leads up to soil in particular.

It is important to keep the bigger picture in mind right through the course of this term. Each structure is broken down to the smallest detail and is later reassembled. Chemistry is the study of matter, its properties, how and why substances combine or separate to form other substances, and how substances interact with energy.

1. Important terminology

DEFINE Atoms: Atoms are the smallest building blocks of matter that cannot be broken down into smaller particles. Atoms make up everything around us.

Colloid: A colloid is a heterogeneous mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance.

Compounds: A compound is formed when two or more elements bond to each other chemically in a strong connection.

Elements: Elements contain only one type of atom and therefore cannot be broken down into smaller substances by chemical means. An element is a pure substance.

Isotopes: Atoms of an element with the same quantity of protons in the core, or the same atomic number, but having different numbers of neutrons and therefore different relative atomic masses.

Matter: Matter is anything that has mass and takes up space. Therefore, matter has mass and volume. Atoms and molecules are all composed of matter.

Mixtures: Pure homogeneous mixtures of substances, which are present in the same phase and consist of two or more substances in the same phase.

Molecules: Molecules are a neutral group of two or more atoms tied together, strong enough to act as a separate unit in a chemical reaction.

Periodic Table: The Periodic Table is a tabular arrangement of the chemical elements, ordered by their atomic number (number of protons in the nucleus) and recurring chemical properties. Elements are arranged according to their chemical and physical properties.

Pure substances: Can be elements or compounds and can have constant compositions, meaning the substances are the same wherever they are found.

Solutions: Solutions can be described as pure homogeneous mixtures of substances, which are present in the same phase.

Suspensions: Suspensions are heterogeneous mixtures containing solid particles that are sufficiently large for sedimentation. Usually the particles must be larger than one micrometre.

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1.1 Matter Matter is anything that has mass and takes up space. Therefore, matter has mass and volume. Atoms and molecules are all composed of matter.

Matter is the stuff from which our physical world is formed, it presents to us as various types of material and exists in the following three phases (also known as the states of matter): • Solids, such as rock.

• A solid has both a definite shape and a definite volume; it is rigid.

• Liquids, such as water.

• A liquid has a distinct volume independent of its container, but has no specific shape.

• Gasses, such as air.

• A gas (also known as vapour) has no fixed volume or shape, but rather conforms to the volume and shape of its container.

Classification of matter Matter is classified in terms of its phase and its composition.

FOR THE CURIOUS A crop farmer may want to know the boron levels because boron is an important trace element for crop growth. He will then have to take samples from all over the farm, perform chemical analysis of all the samples and perform a statistical analysis of the data because the soil is heterogeneous, both under a microscope and over the area of the farm: boron levels will vary from field to field. On the other hand, if the farmer wants to know the pH of the swimming pool, only a single sample is required because the pool can be assumed to be homogeneous.

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Pure substances A pure substance is matter that has a fixed composition and distinct properties – for example, water and table salt (sodium chloride), the primary components of lick salt (for cattle), are pure substances.

Pure substances can be classified as either elements or compounds.

Elements • Elements are pure substances consisting of only one type of atom.

• They cannot be fractioned into simpler materials by chemical methods.

• The smallest particle of an element that can exist on its own, is an atom.

• All the elements are arranged in the Periodic Table according to their properties.

• Examples: phosphorous (P), potassium (K) and oxygen (O2).

• Oxygen is a diatomic element (i.e., it consists naturally out of two atoms that form a molecule), but CO2 (more than one element) is a compound.

What is a diatomic element?

• It is a molecule of the same atoms.

• Some elements cannot exist by themselves; even when they are isolated from any other type of atom they will combine by nature with atoms of the same element in order to be stable.

• Examples: hydrogen (H2), nitrogen (N2), oxygen (O2), fluorine (F2), chlorine (Cl2), bromine (Br2) and iodine (I2).

• The fact that these elements are diatomic only when they are alone, not when chemically bonded to another atom.

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Compounds • • •

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Compounds are substances made of more than one element, thus more than one type of atom.

It does not matter how the compound is made, it will always consist of the same elements in the same mass ratio.

Example: Fertiliser, i.e., calcium nitrate or Ca (NO3)2 is represented as follows:

This compound will always consist out of 1 Ca (calcium) ion, 2 N (nitrogen) ions and 6 O (oxygen) ions.

The smallest particle of a compound that can exist on its own can be a molecule or ions.

Compounds are formed when the atoms of two or more elements are combined chemically and not mechanically. Example: H2O (water molecule):

Compounds can be decomposed (broken down) by simple chemical reactions into elements. The water molecule above can be decomposed with electrolysis into hydrogen and oxygen.

Other examples: Sodium chloride (NaCl), potassium sulphate (K2SO4) and sodium bicarbonate (Na2CO3).

Mixtures Most of the matter we encounter in agriculture consists of mixtures of different substances.

Mixtures are combinations of two or more substances in which each substance retains its own chemical identity and hence, its own properties.

• Mixtures are not pure substances and consist of two or more substances that are mechanically mixed.

• Components are not in a fixed ratio and vary from sample to sample.

• The components keep their own properties.

• The components of a mixture can be separated by mechanical (physical) methods such as filtration, diffusion and distillation.

• Mixtures can be homogeneous or heterogeneous.

• Examples: Air is a mixture of the gasses nitrogen, oxygen and carbon dioxide.

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Differences between homogenous and heterogenous mixtures.

HOMOGENEOUS MIXTURES Substances in the mixture are in the same phase e.g Air (N2 (gas), O2 (gas), CO2 (gas)).

Components cannot be distinguished from each other for e.g salt water (solution of salt in water).

Is a mixture with a uniform composition e.g cool drink (concentrate in water).

Mixtures that are also called solutions, e.g. Gaseous solution: Air – A mixture of two or more gasses.

Gas-liquid solution: Soda water – A gas dissolved in a liquid.

Liquid solution: Water and methanol – A mixture of two or more miscible liquids.

Solid solution: Sea water – a solid dissolved in a liquid.

HETEROGENOUS MIXTURES Substances in the mixture are in different phases e.g mud (Sand in water) Easily distinguishable, e.g feed mix (maize, molasses syrup, ground lucerne and soybean oilcake) Is a mixture with a non-uniform composition, e.g feed mix (dry molasses powder, lucerne and coarse salt) Are not solutions, but rather suspensions, e.g.: Mud (sand in water) Water and oil Conglomerate rock

Heterogeneous mixtures that are very important in agriculture, are colloids.

Colloids do not dissolve in water to form a solution, but they form a mixture with water called a suspension. These are also known as colloidal dispersions because the substances remain dispersed and do not settle to the bottom of the container. (See Unit 2 lesson 16) See the following YouTube video: www.khanacademy.org/science/chemistry/states-of-matter-and-intermolecular-forces/mixtures-andsolutions/v/suspensions-colloids-and-solutions

1.2 Atoms An atom is the basic unit of an element and is a form of matter, which may not be further broken down using any chemical means.

AND: • • • • •

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Any element listed on the Periodic Table consists of atoms.

A typical atom consists of protons, neutrons and electrons.

The atoms of a specific element are identical in size, mass (except for isotopes) and chemical properties.

The atoms of different elements differ from each other.

Atoms can only act as a whole (undivided) and cannot be created or destroyed.

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1.3 Molecules A molecule is the smallest particle of a substance, which exhibits the physical and chemical characteristics of that substance and is a neutral group of two or more atoms tied together, strong enough to act as a separate unit in a chemical reaction.

Examples: Oxygen atom + oxygen atom

oxygen molecule:

+

1.4 The Periodic Table Although precursors exist, Dmitri Mendeleev is generally credited with the publication of the first widely recognised Periodic Table in 1869. He developed his table to illustrate periodic trends in the properties of the then known elements. The Periodic Table is a classification system for all the elements of which existing matter and materials consist.

All elements from atomic numbers 1 (hydrogen) to 118 (ununoctium) have been discovered or reportedly synthesised. As of 2014, the Periodic Table has 114 confirmed elements, comprising elements 1 (hydrogen) to 112 (copernicium), 114 (flerovium) and 116 (livermorium).

A total of 94 elements occur naturally, while the remaining 20 elements, from americium to copernicium, flerovium and livermorium, occur only when synthesised in laboratories.

Each element has a unique name and atomic number representing the number of protons in its nucleus. We can think of each name as a unique ‘label’ that we can use to identify the element. There are two other unique labels that can be used to identify elements. They are the chemical symbol and atomic number. We will learn more about this in the next section.

Each element has certain characteristics of its own and we will see that elements can be grouped together with some similar features. (A full colour version is available on my.Impaq and in Addendum B)

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1.5 Isotopes Not all atoms of an element are identical – atoms of the same element can have different numbers of neutrons. These different versions of the same element are called isotopes.

Atoms and elements are made of protons, neutrons and electrons. The nucleus is made of protons and neutrons – and the electrons surround the nucleus, as shown in the illustration below.

http://www.kyrene.org/cms/lib2/AZ01001083/Centricity/Domain/783/AtomicModel%20Timeline%20 directions%20.pdf

• • • • •

The sum of the number of protons and the number of neutrons is equal to the atomic mass. Therefore: Number of Neutrons = Atomic mass – Atomic number Isotopes are atoms with the same atomic number, but different mass numbers.

Isotopes are never separated in the Periodic Table, they are always grouped together under a single element.

Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses.

Example 1: The element carbon (C), has three isotopes: C-12, C-13 and C-14

http://study.com/academy/lesson/what-are-isotopes-definition-types-examples.html

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The most abundant form of carbon that is found is C-12, with a percentage of 98,9%.

Example 2: The element hydrogen (H), has three isotopes: H-1, H-2 and H-3

http://study.com/academy/lesson/what-are-isotopes-definition-types-examples.html

•

•

•

The three isotopes of carbon as well as the three isotopes of hydrogen all have the same atomic numbers or number of protons, but have different atomic masses.

You may notice, if we look at the atomic masses of elements in the Periodic Table, that they are rarely ever whole numbers, just like for carbon where the atomic mass is 12,011. This is because the atomic mass of carbon is based on the average atomic masses of its isotopes and the abundance of each isotope.

NOTE: The atomic number can either be at the top or bottom of the symbol in the KEY of each element and therefore the atomic mass (also known as the relative atomic mass) can then be the other way around. (See the Periodic Table in Addendum B)

See the following YouTube video: http://study.com/academy/lesson/what-are-isotopes-definition-types-examples.html

USES OF ISOTOPES IN RESEARCH Calcium isotopes are used in clinical research in nutrition studies to find out about the absorption amounts and rates of calcium in the body.

Isotope Ca- 42 Ca- 48 Ca as given in Periodic Table

Atomic number 20 20 20

Atomic mass

42 48 40.08

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Number of Number of protons neutrons 20 22 20 28 20 20

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Magnesium isotopes are also used in absorption studies as well as in heart disease research.

Atomic Atomic number mass Mg- 25 12 25 Mg- 26 12 26 Mg as given in Periodic Table 12 24.31 Isotope

Number of protons 12 12 12

Number of neutrons 13 14 12

2. Differences between: Elements, Compounds and Mixtures ELEMENTS

Pure substance.

Consists of only one type of atom.

Consists of only one type of atom.

A substance that cannot be broken down into simpler substances.

Cannot be separated.

Atom has own, unique properties of element.

Smallest particle is either an atom or diatomic element (molecule of the same atom).

Magnesium (Mg), copper (Cu), potassium (K), phosphorus (P)

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COMPOUNDS

MIXTURES

Pure substance.

Impure substance.

A chemical bond of two or A physical combination of more types of elements. two or more elements and / or compounds.

Consists of the same Quantities of substances in elements in the same a mixture can vary. mass ratio.

A substance that can be A substance that can be broken down into simpler broken down into simpler particles. particles.

Can only be separated by Can be separated by chemical methods. physical methods.

Properties of the Substances in the mixture compound are different retain their unique to the properties of the properties. elements.

Smallest particle is a Particles are according to molecule (covalent bond) composition of mixture. or an ion (ionic bond).

EXAMPLES Water (H2O), Solutions: Sodium chloride (NaCl), Salt dissolved in water. carbon dioxide (CO2) Suspensions: Sand in water.

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3. The basic interpretation of the Periodic Table of elements A full colour version of the following Periodic Table can be downloaded from my.Impaq and is also available in Addendum B.

Characteristics of the periodic table • • •

• • •

The Periodic Table is a table of ALL the elements.

Elements are ordered and grouped according to their chemical and physical properties on the Periodic Table.

Elements are arranged numerically according to their atom numbers, for example hydrogen (1) first, followed by helium (2), etc., so the arrangement is from smallest to largest.

Each element is represented by a letter or a few letters. The symbol for the element is usually an abbreviation of its Latin name, for example Ca for calcium.

There are vertical columns named groups and horizontal rows named periods in the Periodic Table: GROUPS: Numbered across the top of the Periodic Table. ○○ The vertical columns are groups and read from top to bottom. ○○ There are eighteen columns in a Periodic Table and are numbered in: • Roman numerals: group I, II, III, IV, V, VI, VII and O (Traditional system) • and the Algebraic numbers 1 – 18, which are the new numbering system. ○○ All the elements in a specific group have similar chemical properties.

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Periods: ○○ The horizontal rows are periods and read from left to right. ○○ Down the sides of the Periodic Table are the numbers 1 – 7, which number each row. ○○ These periods (horizontal rows) represent the electron shells or energy levels, which encircle the nucleus of each atom. ○○ Example: hydrogen and helium are both in period 1 and have therefore only one energy level. ○○ These electron shells (energy levels) are where the electrons are found. ○○ The seven periods are numbered in Arabic numerals (1, 2, 3, etc.). ○○ Elements are arranged horizontally in periods according to their atomic mass. ○○ In a neutral atom, the number of protons equals the number of electrons.

An atom of an element is represented as follows on the Periodic Table:

○○

○○

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Atomic number (Z): • The atomic number is the number of protons (p+) in the nucleus of the atom.

• Each element has its own atomic number.

• In a neutral atom, the number of electrons = the number of protons.

• Example: Carbon, with an atomic number of 6, has 6 protons and therefore also has 6 electrons.

• Atomic mass (A): • The atomic mass OR mass number (A) is the number of protons (p+) plus neutrons (n) in the nucleus of the atom.

• Therefore A = protons (p+) + neutrons (n) OR n = A – Z • Example: Carbon, with an atomic mass of 12, has 6 protons and 6 neutrons.

• Elements are arranged horizontally in periods according to their atomic mass.

Symbol (E) of the element: • The first letter of the symbol is ALWAYS in upper case and the second letter of the symbol (if there is one) is ALWAYS written in lower case.

• Example: Zinc is Zn. • Elements are arranged left to right and top to bottom in order of increasing atomic number that generally coincides with the increasing atomic mass.

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Example: hydrogen (1) first, followed by helium (2), then lithium (3), etc., so the arrangement is from smallest to largest.

Elements are also broadly divided into metals and non-metals.

Metals • • • • • •

Alkaline metals Group I (1): lithium (Li), sodium (Na), and potassium (K).

Alkaline earth metals Group II (2): beryllium (Be), magnesium (Mg) and calcium (Ca).

Alkaline earth metals are much harder and have higher melting points as alkali metals.

Transition metals between Group II and III (3 to 12): e.g. iron (Fe), zinc (Zn) and silver (Ag). These metals can make more than one type of ion.

Semi metals (also called metalloids): aluminium (Al) and lead (Pb).

Semi metals have some of the properties of metals and some of the properties of nonmetals.

Non-metals • Hydrogen in Group I (1).

• Some elements in Group III, IV, V and VI (Group 13-16).

• Halogens: all the elements in Group VII (Group 17).

• Noble gases: all the elements in group 0 (Group 18).

Properties of metals and non-metals METALS Metals are elements that conduct heat and electricity.

Some metals are malleable and can be pounded into thin sheets. Other metals are ductile and can be stretched into a wire.

Metals are shiny and reflect light.

All metals are solids at room temperature, except mercury (Hg).

NON-METALS Non-metals are elements that do not conduct heat and electricity.

Non-metals are brittle if in a solid state.

Non-metals seldom reflect light, except for carbon in the form of a diamond.

Some non-metals are solids and others are gases at room temperature, except for bromine (Br2), which is a liquid.

IMPORTANT FOR AGRICULTURE A basic understanding of element names, symbols, numbers and how elements bond together is important and integrates into the fields of agriculture, biotechnology, aquaculture, plant and animal science, hydroponics and horticulture. Identifying elements such as nitrogen (which is crucial to plant growth), and evaluating the nutrient needs of plant and animal food, are just two activities, which require a working knowledge of the Periodic Table.

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4. The difference between acids and bases Acids and bases are substances with opposite characteristics and are two types of corrosive substances.

The Brønsted-Lowry definition states that: • An acid is a substance that acts as a proton (H+) donor and therefore provides protons in a solution.

Example: HCl(aq) •

H+(aq) + Cl-(aq)

A base is a substance that acts as a proton (H+) acceptor and therefore receives protons in a solution.

Example: NaOH(aq) • • •

The HCl acts as the proton donor

Na+(aq) + OH-(aq)

The OH-(aq) acts as the proton acceptor

Therefore, acids are proton donors and bases are proton acceptors.

The Brønsted-Lowry definition is accurate for all substances because it is not limited to water as a solvent.

When protons are transferred from an acid to a base, the reaction is called a protolytic reaction or protolysis.

Example: Hydrochloric acid + Water HCl Acid Proton donor

Hydrogen cation + Chloride anion

H 2O

Base Proton acceptor

Ionic reaction: HCl + H2O

H+ OR H3O+

Cl-

Hydrogen cation acid Chloride anion base

H+ + Cl-

HCl is the acid because it is donating a proton (H+) to H2O

H2O is the base because H2O is accepting a proton from HCl •

Note that water is amphoteric, i.e. depending on the circumstances, it can act as either an acid or a base, either donating or accepting a proton. The hydrogen ion (H+) OR hydronium ion (H3O+) is a Brønsted-Lowry acid in aqueous solutions and the hydroxide (OH-) is a base:

https://en.wikipedia.org/wiki/File:Autoprotolyse_eau.svg

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A definition that follows the Brønsted-Lowry concept gives an even wider explanation of acids and bases. It is called the Lewis-concept and describes acids as substances that receive a proton pair and bases as donors of electron pairs, which is a slight contradiction to the previous concept.

Acids and bases neutralise each other in solutions and cause the forming of water and salts. This process is called a neutralisation reaction.

Example: Acid + Base

Water + Salt

Hydrochloric acid + Sodium hydroxide HCl(aq) + NaOH

Water + Sodium chloride

H2O + NaCl

Differences of characteristics of acids and bases ACIDS BASES Any substance with a pH value between 0 A pH value of 7 to 14 is a base. and 7 is considered acidic.

Acids are ionic compounds that break apart Bases are ionic compounds that break in water to form a hydrogen ion (H+). apart to form a negatively charged hydroxide ion (OH-) in water.

Acids taste sour when they are eaten.

Bases taste bitter.

Acids can sting the skin when they are Bases have a slimy or soapy feel on the touched. fingers.

Acids can corrode metals and burn skin.

Strong bases may react violently with acids.

Acids turn blue litmus paper red and turn Bases turn red litmus blue and turn blue or red or orange on universal indicators. green on universal indicators.

Bases that are soluble in water form alkalis (soluble bases).

An acid spill can be safely neutralised by using a mild base.

Bases are substances that contain metal oxides or hydroxides.

Common acids and bases Strong acids HCl hydrochloric acid HNO3 nitric acid H2SO4 sulphuric acid Weak acids CH3COOH acetic acid H2CO3 carbonic acid H3PO4 phosphoric acid

Strong bases NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 barium hydroxide Weak bases NH3 ammonia CH2NH2 methyl amine

Read more: http://www.chemistryexplained.com/A-Ar/Acid-Base-Chemistry.html#ixzz48LVLk9A5

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Strong acids and weak acids

http://www.slideshare.net/jclemenzi/ch-20-21-notes-acids-bases-teacher

A strong acid ionises (dissociates) almost completely in an aqueous solution to form a high concentration of hydrogen ions or protons (H+).

A weak acid ionises (dissociates) only partially in an aqueous solution to form a low concentration of hydrogen ions or protons (H+).

A strong base ionises (dissociates) almost completely in an aqueous solution to form a high concentration of hydroxide ions (OH-).

•A weak base ionises (dissociates) only partially in an aqueous solution to form a low concentration of hydroxide ions (OH-).

• • • •

http://learningchemistryeasily.blogspot.co.za/2013/03/common-solution-equilibria.html?view=magazine

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