Acids and Bases

Acids and Alkalis Aim: To understand the properties of acids and alkalis To identify different chemicals as acid or alkali

Safety Some of the chemicals you will be using in this topic are HAZARDOUS.

You may find various symbols on the bottles containing the acids and alkalis

Corrosive

What do they mean?

What do these hazard symbols mean?

Harmful

Flammable

Irritant

Toxic

Properties of Acids • Strong acids are corrosive and can ‘eat away’ at materials like metal, stone and flesh!

• Weak acids like lemon and vinegar taste sour.

• Acids contain hydrogen (but not all things that contain hydrogen are acids)

Acids

You will often find these acids in the science lab, however they can also be found naturally. Where else may you find them?

What type of acid do these contain?

Citric acid

Tannic acid

Ethanoic acid

Phosphoric acid

Lactic acid

Properties of Bases and Alkalis

•They feel soapy to touch •They are soluble bases

•Like acids they can ‘burn’ the skin •Alkalis contain hydroxide ions

•They taste bitter

Alkalis

In the science lab you will often find these alkalis. Alkalis are also present in these objects: Indigestion tablets Wasp stings Cleaning products

Soap Baking soda

Toothpaste

Using Indicators Aim: Use a range of different indicators to identify acids and alkalis.

Explain the advantages and drawbacks of different indicators.

Using Indicators Indicators work by changing to one colour in acids and another colour in alkalis There are many different indicators, in this experiment you are going to test a few and record what colour they turn in an acidic, alkaline and neutral solution.

During the experiment you will need to remember that sodium hydroxide is alkaline, hydrochloric acid is acidic and water is neutral

Universal Indicator

Aim: Use Universal Indicator to identify acids and alkalis.

Use the pH scale to identify the strength of different acids and alkalis.

The Universal Indicator scale

Neutralisation

Neutralisation Q1. What is the pH of Sodium Hydroxide?

Q2. What is the pH of Hydrochloric acid?

Q3. What volume of Sodium Hydroxide had to be added to neutralise the acid?

Neutralisation Q1. What is the pH of Sodium Hydroxide? 13

Q2. What is the pH of Hydrochloric acid? 1

Q3. What volume of Sodium Hydroxide had to be added to neutralise the acid?

25cm3

Everyday examples of Neutralisation

Everyday examples of Neutralisation

Everyday examples of Neutralisation

Everyday examples of Neutralisation

Neutralisation Aim: Investigate what the products of a neutralisation reaction are.

The Products of Neutralisation Mix together an acid and alkali in an evaporating basin.

What two things need to be kept the same?

The Concentration and Volume of the acid and the alkali needs to be the same.

Using a bunsen burner, tripod, heat proof mat and gauze. Heat the evaporating basin.

What will evaporate from the basin?

Water What will be left in the basin?

A salt

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