Issuu

1 Chemistry in Our Lives Learning Goals • • • •

Define the term chemistry, and identify chemicals. Describe the activities that are part of the scientific method. Identify strategies that are effective for learning. Develop a study plan for learning chemistry. Review math concepts used in chemistry: place values, positive and negative numbers, percentages, solving equations, and interpreting graphs. • Write a number in scientific notation.

Chapter Outline Chapter Opener: Forensic Scientist Chemistry and Chemicals Scientific Method: Thinking Like a Scientist Chemistry Link to Health: Early Chemist: Paracelsus Studying and Learning Chemistry Key Math Skills for Chemistry Writing Numbers in Scientific Notation Clinical Update: Forensic Evidence Helps Solve the Crime

1.1 1.2 1.3 1.4 1.5

Key Math Skills • • • • • •

Identifying Place Values (1.4) Using Positive and Negative Numbers in Calculations (1.4) Calculating Percentages (1.4) Solving Equations (1.4) Interpreting Graphs (1.4) Writing Numbers in Scientific Notation (1.5)

Answers and Solutions to Text Problems 1.1

a. Chemistry is the study of the composition, structure, properties, and reactions of matter. b. A chemical is a substance that has the same composition and properties wherever it is found.

1.2

Your friends may give a variety of definitions, most of which will probably not agree with the dictionary definitions.

1.3

Many chemicals are listed on a bottle of multivitamins such as vitamin A, vitamin B3, vitamin B12, vitamin C, and folic acid.

1.4

Many chemicals are listed on a cereal box such as vitamin A, vitamin B6, vitamin B12, vitamin C, folic acid, sugar, salt, and iron.

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Chapter 1

1.5

Typical items found in a medicine cabinet and some of the chemicals they contain are as follows: Antacid tablets: calcium carbonate, cellulose, starch, stearic acid, silicon dioxide Mouthwash: water, alcohol, thymol, glycerol, sodium benzoate, benzoic acid Cough suppressant: menthol, beta-carotene, sucrose, glucose

1.6

Typical chemicals found in dishwashing products are: water, sodium lauryl sulfate, sodium laureth sulfate, dimethyl amine oxide, sodium chloride, phenoxyethanol.

1.7

a. observation d. observation

b. hypothesis e. observation

c. experiment f. conclusion

1.8

a. observation d. experiment

b. hypothesis e. observation

c. experiment f. hypothesis

1.9

a. observation

b. hypothesis

c. experiment

d. experiment

1.10 a. hypothesis

b. observation

c. experiment

d. conclusion

1.11 There are several things you can do that will help you successfully learn chemistry, including attending class regularly, forming a study group, reading the assigned pages in the textbook before class, answering the Engage questions as you read new material in the textbook, trying to solve the Sample Problems first before reading the provided Solutions, working the Study Checks and Practice Problems and checking the Answers, self-testing during and after reading each Section, retesting on new information a few days later, going to the instructor’s office hours, and keeping a problem notebook. 1.12 Many things make it difficult to learn chemistry, including not going to class regularly, not working Sample Problems and Study Checks, not reading the assignment ahead of class, not going to the instructor’s office hours, and waiting until the night before an exam to study. 1.13 Ways you can enhance your learning of chemistry include: a. forming a study group. c. asking yourself questions while reading the text. e. answering the Engage questions. 1.14 Ways you can enhance your learning of chemistry include: a. studying different topics at the same time. c. attending review sessions. d. working the problems again after a few days. e. keeping a problem notebook. 1.15 a. The bolded 8 is in the thousandths place. b. The bolded 6 is in the ones place. c. The bolded 6 is in the hundreds place. 1.16 a. The bolded 5 is in the tenths place. b. The bolded 7 is in the tens place. c. The bolded 0 is in the hundredths place. 1.17 a. 15 - (-8) = 15 + 8 = 23 b. -8 + (-22) = -30 c. 4 * (-2) + 6 = -8 + 6 = -2 1.18 a. -11 - (-9) = -11 + 9 = -2 b. 34 + (-55) = -21 -56 = -7 c. 8 1.19 a. The graph shows the relationship between the temperature of a cup of tea and time. b. The vertical axis measures temperature, in °C.

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Chemistry in Our Lives

c. The values on the vertical axis range from 20 °C to 80 °C. d. As time increases, the temperature decreases. 1.20 a. The horizontal axis measures time, in minutes. b. The values on the horizontal axis range from 0 min to 100 min. c. After 20 min, the temperature of the tea is about 56 °C. d. About 38 min were required for the tea to reach a temperature of 45 °C. 4a + 4 = 40 1.21 a. 4a + 4 - 4 = 40 - 4 4a = 36 4a 36 = 4 4 a = 9 a b. = 7 6 a 6 a b = 6(7) 6 a = 42 1.22 a. 2b + 7 = b + 10 2b + 7 - 7 = b + 10 - 7 2b = b + 3 2b - b = b - b + 3 b = 3 b. 3b - 4 = 24 - b 3b - 4 + 4 = 24 - b + 4 3b = 28 - b 3b + b = 28 - b + b 4b = 28 4b 28 = 4 4 b = 7 21 flu shots * 100, = 84, received flu shots 25 patients b. total grams of alloy = 56 g silver + 22 g copper = 78 g of alloy 56 g silver * 100, = 72, silver 78 g alloy c. total number of coins = 11 nickels + 5 quarters + 7 dimes = 23 coins 7 dimes * 100, = 30, dimes 23 coins

1.23 a.

22 boys * 100, = 63, boys 35 babies b. total grams of alloy = 67 g gold + 35 g zinc = 102 g of alloy 35 g zinc * 100, = 34, zinc 102 g alloy c. total number of coins = 15 pennies + 14 dimes + 6 quarters = 35 coins 15 pennies * 100, = 43, pennies 35 coins

1.24 a.

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Chapter 1

c. The values on the vertical axis range from 20 °C to 40 °C. d. As time increases, the temperature decreases. 1.26 a. The horizontal axis measures time, in hours, since death. b. The values on the horizontal axis range from 0 h to 25 h. c. About 15 hours were needed to reach a body temperature of 28 °C. d. Since it takes about 5 hours to reach a body temperature of 34 °C, the time of death is estimated to be (9 p.m. – 5 h =) 4 p.m. 1.27 a. Move the decimal point four places to the left to give 5.5 * 104. b. Move the decimal point two places to the left to give 4.8 * 102. c. Move the decimal point six places to the right to give 5 * 10-6. d. Move the decimal point four places to the right to give 1.4 * 10-4. e. Move the decimal point three places to the right to give 7.2 * 10-3. f. Move the decimal point five places to the left to give 6.7 * 105. 1.28 a. Move the decimal point eight places to the left to give 1.8 * 108. b. Move the decimal point five places to the right to give 6 * 10-5. c. Move the decimal point two places to the left to give 7.5 * 102. d. Move the decimal point one place to the right to give 1.5 * 10-1. e. Move the decimal point two places to the right to give 2.4 * 10-2. f. Move the decimal point three places to the left to give 1.5 * 103. 1.29 a. 7.2 * 103, which is also 7200, is larger than 8.2 * 102 or 820. b. 3.2 * 10-2, which is also 0.032, is larger than 4.5 * 10-4 or 0.000 45. c. 1 * 104, which is also 10 000, is larger than 1 * 10-4 or 0.0001. d. 6.8 * 10-2, which is also 0.068, is larger than 0.000 52. 1.30 a. 5.5 * 10-9, which is also 0.000 000 005 5, is smaller than 4.9 * 10-3 or 0.0049. b. 3.4 * 102, which is also 340, is smaller than 1250. c. 0.000 000 4 is smaller than 5.0 * 102 or 500. d. 2.50 * 102, which is also 250, is smaller than 4 * 105 or 400 000. 1.31 a. hypothesis

b. conclusion

c. experiment

d. observation

1.32 a. hypothesis

b. experiment

c. observation

d. conclusion

1.33

120 g ethylene glycol * 100, = 27, ethylene glycol 450 g liquid

1.34

1.5 g ethylene glycol * 100, = 0.15, ethylene glycol 1000 g body mass

1.35 No. All of these ingredients are chemicals. 1.36 No. All of these ingredients are chemicals. 1.37 Yes. Sherlock’s investigation includes making observations (gathering data), formulating a hypothesis, testing the hypothesis, and modifying it until one of the hypotheses is validated. 1.38 Holmes stresses the important first step of the scientific method: making observations and collecting data. 1.39 a. When two negative numbers are added, the answer has a negative sign. b. When a positive and negative number are multiplied, the answer has a negative sign. 1.40 a. When a negative number is subtracted from a positive number, the answer has a positive sign. b. When two negative numbers are divided, the answer has a positive sign. 1.41 a. Describing the appearance of a patient is an observation. b. Formulating a reason for the extinction of dinosaurs is a hypothesis. c. Measuring a patient’s blood pressure is an observation.

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Chemistry in Our Lives

1.42 a. Measuring the composition of a sample is an observation. b. Recording a change in a sample is an observation. c. Formulating a reason as to why a phenomenon has happened is a hypothesis. 1.43 If experimental results do not support your hypothesis, you should: b. modify your hypothesis. c. do more experiments. 1.44 A hypothesis is confirmed when: b. many experiments validate the hypothesis. 1.45 A successful study plan would include: b. working the Sample Problems as you go through a chapter. c. self-testing. 1.46 A successful study plan would include: b. forming a study group and discussing the problems together. c. working problems in a notebook for easy reference. 1.47 a. 4 * (-8) = -32 b. -12 - 48 = -12 + (-48) = -60 -168 c. = 42 -4 1.48 a. -95 - (-11) = -95 + 11 = -84 152 b. = -8 -19 c. 4 - 56 = 4 + (-56) = -52 1.49 total number of gumdrops = 16 orange + 8 yellow + 16 black = 40 gumdrops 8 yellow gumdrops a. * 100, = 20, yellow gumdrops 40 total gumdrops 16 black gumdrops b. * 100, = 40, black gumdrops 40 total gumdrops 1.50 total number of students = 12 As + 18 Bs + 20 Cs = 50 students 18 Bs * 100, = 36, Bs a. 50 total students 20 Cs * 100, = 40, Cs b. 50 total students 1.51 a. Move the decimal point five places to the left to give 1.2 * 105. b. Move the decimal point seven places to the right to give 3.4 * 10-7. c. Move the decimal point two places to the right to give 6.6 * 10-2. d. Move the decimal point three places to the left to give 2.7 * 103. 1.52 a. Move the decimal point three places to the right to give 4.2 * 10-3. b. Move the decimal point two places to the left to give 3.1 * 102. c. Move the decimal point eight places to the left to give 8.9 * 108. d. Move the decimal point eight places to the right to give 5.6 * 10-8. 1.53 a. observation

b. hypothesis

c. conclusion

1.54 a. observation

b. experiment

c. conclusion

1.55 a. Self-testing allows you to check on what you understand. b. Forming a study group can motivate you to study, fill in gaps, and correct misunderstandings by teaching and learning together. c. Reading the assignment before class prepares you to learn new material. Copyright © 2019 Pearson Education, Inc.

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Chapter 1

1.56 a. Studying only the night before an exam does not allow you time to make connections between new and previously learned information for longer lasting memory and more efficient retrieval of the information. b. Not going to class does not allow you to interact with your professor and peers. Class can give you another perspective on the material; the professor may go over examples or applications not covered in the textbook, and student questions and discussion may elaborate on the material or provide new insights. c. Not practicing the problems in the text does not allow you to apply problem solving to the new concepts you are learning. 1.57 a. observation

b. hypothesis

c. experiment

d. conclusion

1.58 a. observation

b. hypothesis

c. observation

d. observation

2x + 5 = 41 1.59 a. 2x + 5 - 5 = 41 - 5 2x = 36 2x 36 = 2 2 x = 18 5x = 40 b. 3 5x 3 a b = 3(40) 3 5x = 120 5x 120 = 5 5 x = 24 1.60 a. 3z - (-6) = 12 3z + 6 = 12 3z + 6 - 6 = 12 - 6 3z = 6 3z 6 = 3 3 z = 2 4z b. = -8 -12 4z -12 a b = -12(-8) -12 4z = 96 4z 96 = 4 4 z = 24 1.61 a. The graph shows the relationship between the solubility of carbon dioxide in water and temperature. b. The vertical axis measures the solubility of carbon dioxide in water (g CO2/100 g water). c. The values on the vertical axis range from 0 to 0.35 g CO2/100 g water. d. As temperature increases, the solubility of carbon dioxide in water decreases. 1.62 a. The horizontal axis measures temperature, in °C. b. The values on the horizontal axis range from 0 °C to 60 °C. c. At 25 °C, the solubility of carbon dioxide in water is about 0.17 g CO2/100 g water. d. Carbon dioxide has a solubility of 0.20 g CO2/100 g water at a temperature of about 16 °C.

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2 Chemistry and Measurements Learning Goals • Write the names and abbreviations for the metric and SI units used in measurements of volume, length, mass, temperature, and time. • Identify a number as measured or exact; determine the number of significant figures in a measured number. • Give the correct number of significant figures for a calculated answer. • Use the numerical values of prefixes to write a metric equality. • Write a conversion factor for two units that describe the same quantity. • Use conversion factors to change from one unit to another. • Calculate the density of a substance; use the density to calculate the mass or volume of a substance.

Chapter Outline Chapter Opener: Registered Nurse Units of Measurement Measured Numbers and Significant Figures Significant Figures in Calculations Prefixes and Equalities Writing Conversion Factors Problem Solving Using Unit Conversion Chemistry Link to Health: Toxicology and Risk–Benefit Assessment Density Chemistry Link to Health: Bone Density Clinical Update: Greg’s Visit with His Doctor

2.1 2.2 2.3 2.4 2.5 2.6 2.7

Key Math Skill • Rounding Off (2.3)

Core Chemistry Skills • • • • • •

Counting Significant Figures (2.2) Using Significant Figures in Calculations (2.3) Using Prefixes (2.4) Writing Conversion Factors from Equalities (2.5) Using Conversion Factors (2.6) Using Density as a Conversion Factor (2.7)

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Chapter 2

Answers and Solutions to Text Problems 2.1

a. The abbreviation for the unit gram is g. b. The abbreviation for the unit degree Celsius is °C. c. The abbreviation for the unit liter is L. d. The abbreviation for the unit pound is lb. e. The abbreviation for the unit second is s.

2.2

a. The abbreviation for the unit kilogram is kg. b. The abbreviation for the unit kelvin is K. c. The abbreviation for the unit quart is qt. d. The abbreviation for the unit meter is m. e. The abbreviation for the unit centimeter is cm.

2.3

a. A liter is a unit of volume. b. A centimeter is a unit of length. c. A kilometer is a unit of length. d. A second is a unit of time.

2.4

a. A kilometer is a unit of length. b. A kilogram is a unit of mass. c. A degree Celsius is a unit of temperature. d. A liter is a unit of volume.

2.5

a. The unit is a meter, which is a unit of length. b. The unit is a gram, which is a unit of mass. c. The unit is a milliliter, which is a unit of volume. d. The unit is a second, which is a unit of time. e. The unit is a degree Celsius, which is a unit of temperature.

2.6

a. The unit is a liter, which is a unit of volume. b. The unit is a centimeter, which is a unit of length. c. The unit is a kilogram, which is a unit of mass. d. The unit is an hour, which is a unit of time. e. The unit is a kelvin, which is a unit of temperature.

2.7

a. The unit is a second, which is a unit of time. b. The unit is a kilogram, which is a unit of mass. c. The unit is a gram, which is a unit of mass. d. The unit is a degree Celsius, which is a unit of temperature.

2.8

a. The unit is a degree Celsius, which is a unit of temperature. b. The unit is a second, which is a unit of time. c. The unit is a milliliter, which is a unit of volume. d. The unit is a gram, which is a unit of mass.

2.9

a. All five numbers are significant figures (5 SFs). b. Only the two nonzero numbers are significant (2 SFs); the preceding zeros are placeholders. c. Only the two nonzero numbers are significant (2 SFs); the zeros that follow are placeholders. d. All three numbers in the coefficient of a number written in scientific notation are significant (3 SFs). e. All four numbers to the right of the decimal point, including the last zero in the decimal number, are significant (4 SFs). f. All three numbers, including the zeros at the end of a decimal number, are significant (3 SFs).

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Chemistry and Measurements

2.10 a. All four numbers, including the last zero, in a decimal number, are significant (4 SFs). b. All six numbers are significant figures (6 SFs). c. All three numbers, including the zeros at the end of a decimal number, are significant (3 SFs). d. All three numbers are significant figures (3 SFs). e. There are three significant figures (3 SFs), since the zero between the two nonzero numbers is significant; the zeros that follow are placeholders only. f. Both of the numbers in the coefficient of a number written in scientific notation are significant (2 SFs). 2.11 Both measurements in part b have three significant figures, and both measurements in part c have two significant figures. 2.12 Both measurements in part a have three significant figures. 2.13 a. Zeros at the beginning of a decimal number are not significant. b. Zeros between nonzero digits are significant. c. Zeros at the end of a decimal number are significant. d. Zeros in the coefficient of a number written in scientific notation are significant. e. Zeros used as placeholders in a large number without a decimal point are not significant. 2.14 a. Zeros between nonzero digits are significant. b. Zeros at the end of a decimal number are significant. c. Zeros at the beginning of a decimal number are not significant. d. Zeros used as placeholders in a large number without a decimal point are not significant. e. Zeros in the coefficient of a number written in scientific notation are significant. 2.15 a. 5000 L is the same as 5 * 1000 L, which is written in scientific notation as 5.0 * 103 L with two significant figures. b. 30 000 g is the same as 3 * 10 000 g, which is written in scientific notation as 3.0 * 104 g with two significant figures. c. 100 000 m is the same as 1 * 100 000 m, which is written in scientific notation as 1.0 * 105 m with two significant figures. 1 d. 0.000 25 cm is the same as 2.5 * cm, which is written in scientific notation as 10 000 2.5 * 10-4 cm. 2.16 a. 5 100 000 g is the same as 5.1 * 1 000 000 g, which is written in scientific notation as 5.1 * 106 g. b. 26 000 s is the same as 2.6 * 10 000 s, which is written in scientific notation as 2.6 * 104 s. c. 40 000 m is the same as 4 * 10 000 m, which is written in scientific notation as 4.0 * 104 m with two significant figures. 1 d. 0.000 820 kg is the same as 8.2 * kg, which is written in scientific notation as 10 000 -4 8.2 * 10 kg. 2.17 Measured numbers are obtained using some type of measuring device. Exact numbers are numbers obtained by counting items or using a definition that compares two units in the same measuring system. a. The value 67.5 kg is a measured number; measurement of mass requires a measuring device. b. The value 2 tablets is obtained by counting, making it an exact number. c. The values in the metric definition 1 L = 1000 mL are exact numbers. d. The value 1720 km is a measured number; measurement of distance requires a measuring device.

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Chapter 2

2.18 Measured numbers are obtained using some type of measuring device. Exact numbers are numbers obtained by counting items or using a definition that compares two units in the same measuring system. a. The value 31 students is obtained by counting, making it an exact number. b. The value 1.20 * 108 yr is a measured number; measurement of time requires a measuring device. c. The value 104 kg is a measured number; measurement of mass requires a measuring device. d. The value 184 mg/dL is a measured number; measurement of mass and volume requires measuring devices. 2.19 Measured numbers are obtained using some type of measuring device. Exact numbers are numbers obtained by counting items or using a definition that compares two units in the same measuring system. a. 6 oz of hamburger meat is a measured number (3 hamburgers is a counted/exact number). b. Neither are measured numbers (both 1 table and 4 chairs are counted/exact numbers). c. Both 0.75 lb of grapes and 350 g of butter are measured numbers. d. Neither are measured numbers (the values in a definition are exact numbers). 2.20 Measured numbers are obtained using some type of measuring device. Exact numbers are numbers obtained by counting items or using a definition that compares two units in the same measuring system. a. 5 pizzas is a counted/exact number (50.0 g of cheese is a measured number). b. 6 nickels is a counted/exact number (16 g of nickel is a measured number). c. 3 onions is a counted/exact number (3 lb of onions is a measured number). d. 5 cars is a counted/exact number (5 miles is a measured number). 2.21 a. 1.607 kg is a measured number and has 4 SFs. b. 130 mcg is a measured number and has 2 SFs. c. 4.02 * 106 red blood cells is a measured number and has 3 SFs. d. 23 babies is a counted/exact number. 2.22 a. 103.5 °F is a measured number and has 4 SFs. b. 21 tablets is a counted/exact number. c. 0.46 s is a measured number and has 2 SFs. d. 1.20 * 1010 neurons is a measured number and has 3 SFs. 2.23 a. 1.85 kg; the last digit is dropped since it is 4 or less. b. 88.2 L; since the fourth digit is 4 or less, the last three digits are dropped. c. 0.004 74 cm; since the fourth significant digit (the first digit to be dropped) is 5 or greater, the last retained digit is increased by 1 when the last four digits are dropped. d. 8810 m; since the fourth significant digit (the first digit to be dropped) is 5 or greater, the last retained digit is increased by 1 when the last digit is dropped (a nonsignificant zero is added at the end as a placeholder). e. 1.83 * 105 s; since the fourth digit is 4 or less, the last digit is dropped. The * 105 is retained so that the magnitude of the answer is not changed. 2.24 a. 1.9 kg; since the third significant digit (the first digit to be dropped) is 5 or greater, the last retained digit is increased by 1 when the last two digits are dropped. b. 88 L; since the third significant digit is 4 or less, the last four digits are dropped. c. 0.0047 cm; since the third significant digit is 4 or less, the last five digits are dropped. d. 8800 m; since the third digit is 4 or less, the last digit is changed to a zero as a placeholder. e. 1.8 * 105 s; since the third digit is 4 or less, the last two digits are dropped. The * 105 is retained so that the magnitude of the answer is not changed.

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Chemistry and Measurements

2.25 a. To round off 56.855 m to three significant figures, drop the final digits 55 and increase the last retained digit by 1 to give 56.9 m. b. To round off 0.002 282 g to three significant figures, drop the final digit 2 to give 0.002 28 g. c. To round off 11 527 s to three significant figures, drop the final digits 27 and add two zeros as placeholders to give 11 500 s (1.15 * 104 s). d. To express 8.1 L to three significant figures, add a significant zero to give 8.10 L. 2.26 a. To round off 3.2805 m to two significant figures, drop the final digits 805 and increase the last retained digit by 1 to give 3.3 m. b. To round off 1.855 * 102 g to two significant figures, drop the final digits 55 and increase the last retained digit by 1 to give 1.9 * 102 g. c. To round off 0.002 341 mL to two significant figures, drop the final digits 41 to give 0.0023 mL. d. To express 2 L to two significant figures, add a significant zero to give 2.0 L. 2.27 a. 45.7 * 0.034 = 1.6 Two significant figures are allowed since 0.034 has 2 SFs. b. 0.002 78 * 5 = 0.01 One significant figure is allowed since 5 has 1 SF. 34.56 c. = 27.6 Three significant figures are allowed since 1.25 has 3 SFs. 1.25 (0.2465)(25) d. = 3.5 Two significant figures are allowed since 25 has 2 SFs. 1.78 e. (2.8 * 104)(5.05 * 10-6) = 0.14 or 1.4 * 10-1 Two significant figures are allowed since 2.8 * 104 has 2 SFs. (3.45 * 10-2)(1.8 * 105) f. = 0.8 or 8 * 10-1 One significant figure is allowed since (8 * 103) 8 * 103 has 1 SF. 2.28 a. 400 * 185 = 7 * 104 One significant figure is allowed since 400 has 1 SF. 2.40 b. = 0.005 or 5 * 10-3 One significant figure is allowed since 4 has 1 SF. (4)(125) c. 0.825 * 3.6 * 5.1 = 15 Two significant figures are allowed since 3.6 and 5.1 both have 2 SFs. (3.5)(0.261) = 0.0055 or 5.5 * 10-3 Two significant figures are allowed since 3.5 has 2 SFs. d. (8.24)(20.0) (5 * 10-5)(1.05 * 104) e. = 6 * 106 One significant figure is allowed since 5 * 10-5 (8.24 * 10-8) has 1 SF. (4.25 * 102)(2.56 * 10-3) f. = 8.58 Three significant figures are allowed since 56.5 (2.245 * 10-3)(56.5) (and others) has 3 SFs. 2.29 a. 45.48 + 8.057 = 53.54 Two decimal places are allowed since 45.48 has two decimal places. b. 23.45 + 104.1 + 0.025 = 127.6 One decimal place is allowed since 104.1 has one decimal place. c. 145.675 - 24.2 = 121.5 One decimal place is allowed since 24.2 has one decimal place. d. 1.08 - 0.585 = 0.50 Two decimal places are allowed since 1.08 has two decimal places. e. 2300 + 196.11 = 2500 Answer is rounded off to the hundreds place since 2300 is expressed to the hundreds place. f. 145.111 - 22.9 + 34.49 = 156.7 One decimal place is allowed since 22.9 has one decimal place.

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Chapter 2

2.30 a. 5.08 + 25.1 = 30.2 One decimal place is allowed since 25.1 has one decimal place. b. 85.66 + 104.10 + 0.025 = 189.79 Two decimal places are allowed since 85.66 and 104.10 have two decimal places. c. 24.568 - 14.25 = 10.32 Two decimal places are allowed since 14.25 has two decimal places. d. 0.2654 - 0.2585 = 0.0069 Four decimal places are allowed since both numbers have four decimal places. e. 66.77 + 17 - 0.33 = 83 Answer is rounded off to the ones place since 17 is expressed to the ones place. f. 460 - 33.77 = 430 Answer is rounded off to the tens place since 460 is expressed to the tens place. 2.31 a. mg

b. dL

c. km

d. pg

2.32 a. Gg

b. Mm

c. mL or mcL

d. fs

2.33 a. centiliter

b. kilogram

c. millisecond

d. petameter

2.34 a. deciliter

b. terasecond

c. microgram

d. picometer

2.35 a. 0.01 c. 0.001 (or 1 * 10-3)

b. 1 000 000 000 000 (or 1 * 1012) d. 0.1

2.36 a. 1 000 000 000 (or 1 * 109) c. 1 000 000 (or 1 * 106)

b. 0.000 001 (or 1 * 10-6) d. 0.000 000 001 (or 1 * 10-9)

2.37 a. decigram

b. microgram

c. kilogram

d. centigram

2.38 a. gigameter

b. megameter

c. millimeter

d. picometer

2.39 a. 1 m = 100 cm c. 1 mm = 0.001 m

b. 1 m = 1 * 109 nm d. 1 L = 1000 mL

2.40 a. 1 Mg = 1 * 106 g c. 1 g = 0.001 kg

b. 1 mL = 1000 mL d. 1 g = 1000 mg

2.41 a. kilogram, since 103 g is greater than 10-3 g b. milliliter, since 10-3 L is greater than 10-6 L c. km, since 103 m is greater than 100 m d. kL, since 103 L is greater than 10-1 L e. nanometer, since 10-9 m is greater than 10-12 m 2.42 a. mg, since 10-3 g is smaller than 100 g b. nanometer, since 10-9 m is smaller than 10-2 m c. micrometer, since 10-6 m is smaller than 10-3 m d. mL, since 10-3 L is smaller than 10-1 L e. centigram, since 10-2 g is smaller than 106 g

1m 100 cm and 100 cm 1m 2.44 You can check that you have written the correct conversion factors for an equality by looking at the number and units in each; the information on one side of the equality appears in the numerator of a conversion factor while the information on the other side of the equality appears in the denominator. To generate a second conversion factor, we invert the first conversion factor so the numbers and units in the numerator and denominator switch places. 2.43 A conversion factor can be inverted to give a second conversion factor:

100 cm 1m and 1m 100 cm 1 * 109 ng 1g and b. 1 g = 1 * 109 ng; 1g 1 * 109 ng

2.45 a. 1 m = 100 cm;

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Chemistry and Measurements

1000 L 1 kL and 1 kL 1000 L 1000 ms 1s and d. 1 s = 1000 ms; 1s 1000 ms 100 mm 1 dm e. 1 dm = 100 mm; and 1 dm 100 mm 2.54 cm 1 in. 2.46 a. 1 in. = 2.54 cm; and 1 in. 2.54 cm 0.621 mi 1 km b. 1 km = 0.621 mi; and 1 km 0.621 mi 454 g 1 lb and c. 1 lb = 454 g; 1 lb 454 g 10 dL 1L d. 1 L = 10 dL; and 1L 10 dL 12 1 * 10 pg 1g and e. 1 g = 1 * 1012 pg; 1g 1 * 1012 pg c. 1 kL = 1000 L;

1 yd 3 ft and ; the 1 yd and 3 ft are both exact (U.S. definition). 1 yd 3 ft 1 kg 2.20 lb b. 1 kg = 2.20 lb; and ; the 2.20 lb is measured: it has 3 SFs; the 1 kg is exact. 1 kg 2.20 lb 1 gal gasoline 27 mi c. 1 gal of gasoline = 27 mi; and ; the 27 mi is measured: 1 gal gasoline 27 mi it has 2 SFs; the 1 gal is exact. 93 g silver 100 g sterling d. 100 g of sterling = 93 g of silver; and ; the 93 g is measured: 100 g sterling 93 g silver it has 2 SFs; the 100 g is exact. 60 sec 1 min and ; the 1 min and 60 sec are both exact. e. 1 min = 60 sec; 1 min 60 sec 2.47 a. 1 yd = 3 ft;

2.48 a. 1 L = 1.06 qt;

1.06 qt 1L and ; the 1.06 qt is measured: it has 3 SFs; the 1 L is exact. 1L 1.06 qt

b. 1 lb of oranges = +1.29;

1 lb oranges +1.29 and ; the $1.29 is measured: it has 1 lb oranges +1.29

3 SFs; the 1 lb is exact. 7 days 1 week c. 1 week = 7 days; and ; the 1 week and 7 days are both exact. 1 week 7 days

100 mL 1 dL and ; the 1 dL and 100 mL are both exact 1 dL 100 mL (metric definition). 75 g gold 100 g gold ring and ; the 75 g is e. 100 g of gold ring = 75 g of gold; 100 g gold ring 75 g gold measured: it has 2 SFs; the 100 g is exact. d. 1 dL = 100 mL;

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Chapter 2

3.5 m 1s and ; the 3.5 m is measured: it has 2 SFs; the 1 s is exact. 1s 3.5 m 3.5 g potassium 1 day b. 1 day = 3.5 g of potassium; and ; the 3.5 g is measured: 1 day 3.5 g potassium it has 2 SFs; the 1 day is exact. 1 L gasoline 26.0 km c. 1 L of gasoline = 26.0 km; and ; the 26.0 km is measured: 1 L gasoline 26.0 km it has 3 SFs; the 1 L is exact. 29 mcg pesticide 1 kg plums d. 1 kg of plums = 29 mcg of pesticide; and ; the 29 mcg 1 kg plums 29 mcg pesticide is measured: it has 2 SFs; the 1 kg is exact. 28.2 g silicon 100 g crust e. 100 g of crust = 28.2 g of silicon; and ; the 28.2 g is measured: 100 g crust 28.2 g silicon it has 3 SFs; the 100 g is exact. 2.49 a. 1 s = 3.5 m;

150 mcg iodine 1 day and ; the 150 mcg is measured: 1 day 150 mcg iodine it has 2 SFs; the 1 day is exact. 32 mg nitrate 1 kg water and ; the 32 mg is measured: b. 1 kg of water = 32 mg of nitrate; 1 kg water 32 mg nitrate it has 2 SFs; the 1 kg is exact. 58 g gold 100 g jewelry c. 100 g of jewelry = 58 g of gold; and ; the 58 g is measured: 100 g jewelry 58 g gold it has 2 SFs; the 100 g is exact. +1.65 1 L milk and ; the $1.65 is measured: it has 3 SFs; the 1 L d. 1 L of milk = +1.65; 1 L milk +1.65 is exact. 1000 kg 1 metric ton and ; the 1 metric ton and e. 1 metric ton = 1000 kg; 1 metric ton 1000 kg 1000 kg are both exact (metric definition). 2.50 a. 1 day = 150 mcg of iodine;

630 mg calcium 1 tablet and ; the 630 mg is 1 tablet 630 mg calcium measured: it has 2 SFs; the 1 tablet is exact. 60 mg vitamin C 1 day and ; the 60 mg is b. 1 day = 60 mg of vitamin C; 1 day 60 mg vitamin C measured: it has 1 SF; the 1 day is exact. 50 mg atenolol 1 tablet and ; the 50 mg is c. 1 tablet = 50 mg of atenolol; 1 tablet 50 mg atenolol measured: it has 1 SF; the 1 tablet is exact. 81 mg aspirin 1 tablet d. 1 tablet = 81 mg of aspirin; and ; the 81 mg is measured: 1 tablet 81 mg aspirin it has 2 SFs; the 1 tablet is exact. 2.51 a. 1 tablet = 630 mg of calcium;

10 mg furosemide 1 mL and ; the 10 mg is 1 mL 10 mg furosemide measured: it has 1 SF; the 1 mL is exact. 70. mcg selenium 1 day and ; the 70. mcg is b. 1 day = 70. mcg of selenium; 1 day 70. mcg selenium measured: it has 2 SFs; the 1 day is exact. 2.52 a. 1 mL = 10 mg of furosemide;

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Chemistry and Measurements

85 mL saline solution 1 hour and ; 1 hour 85 mL saline solution the 85 mL is measured: it has 2 SFs; the 1 hour is exact. 360 mg omega@3 fatty acids and d. 1 capsule = 360 mg of omega-3 fatty acids; 1 capsule 1 capsule ; the 360 mg is measured: it has 2 SFs; the 1 capsule is exact. 360 mg omega@3 fatty acids c. 1 hour = 85 mL of saline solution;

10 mg Atarax 5 mL syrup and 5 mL syrup 10 mg Atarax 0.25 g Lanoxin 1 tablet b. 1 tablet = 0.25 g of Lanoxin; and 1 tablet 0.25 g Lanoxin 300 mg Motrin 1 tablet c. 1 tablet = 300 mg of Motrin; and 1 tablet 300 mg Motrin

2.53 a. 5 mL of syrup = 10 mg of Atarax;

2.5 mg Coumadin 1 tablet and 1 tablet 2.5 mg Coumadin 100 mg Clozapine 1 tablet b. 1 tablet = 100 mg of Clozapine; and 1 tablet 100 mg Clozapine 1.5 g Cefuroxime 1 mL solution c. 1 mL of solution = 1.5 g of Cefuroxime; and 1 mL solution 1.5 g Cefuroxime

2.54 a. 1 tablet = 2.5 mg of Coumadin;

2.55 a. Given

44.2 mL Need liters 1L Plan mL S L 1000 mL 1L Set-up 44.2 mL * = 0.0442 L (3 SFs) 1000 mL b. Given 8.65 m Need nanometers 1 * 109 nm Plan m S nm 1m 1 * 109 nm Set-up 8.65 m * = 8.65 * 109 nm (3 SFs) 1m c. Given 5.2 * 108 g Need megagrams 1 Mg

Plan

g S Mg

2.56 a. Given

4.82 * 10-5 L Need

1 * 106 g 1 Mg Set-up 5.2 * 108 g * = 5.2 * 102 Mg (2 SFs) 1 * 106 g d. Given 0.72 ks Need milliseconds 1000 s 1000 ms Plan ks S s S ms 1 ks 1s 1000 s 1000 ms Set-up 0.72 ks * * = 7.2 * 105 ms (2 SFs) 1 ks 1s picoliters

Plan Set-up

1 * 10 pL 1L 1 * 1012 pL 4.82 * 10-5 L * = 4.82 * 107 pL (3 SFs) 1L

L S pL

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Chapter 2

b. Given 575.2 dm Need kilometers 1m 1 km Plan dm S m S km 10 dm 1000 m 1m 1 km * = 0.057 52 km (4 SFs) Set-up 575.2 dm * 10 dm 1000 m c. Given 5 * 10-4 kg Need micrograms 1000 g 1 * 106 mg Plan kg S g S mg 1 kg 1g 1000 g 1 * 106 mg * = 5 * 105 mg (1 SF) Set-up 5 * 10-4 kg * 1 kg 1g d. Given 6.4 * 1010 ps Need seconds 1s Plan ps S s 1 * 1012 ps 1s Set-up 6.4 * 1010 ps * = 0.064 s (2 SFs) 1 * 1012 ps 2.57 a. Given

3.428 lb Need kilograms 1 kg Plan lb S kg 2.20 lb 1 kg = 1.56 kg (3 SFs) Set-up 3.428 lb * 2.20 lb b. Given 1.6 m Need inches 39.4 in. Plan m S in. 1m 39.4 in. = 63 in. (2 SFs) Set-up 1.6 m * 1m c. Given 4.2 L Need quarts 1.06 qt Plan L S qt 1L 1.06 qt = 4.5 qt (2 SFs) Set-up 4.2 L * 1L d. Given 0.672 ft Need millimeters 12 in. 2.54 cm 10 mm Plan ft S in. S cm S mm 1 ft 1 in. 1 cm 12 in. 2.54 cm 10 mm * * = 205 mm (3 SFs) Set-up 0.672 ft * 1 ft 1 in. 1 cm 2.58 a. Given 0.21 lb Need grams 454 g Plan lb S g 1 lb 454 g = 95 g (2 SFs) Set-up 0.21 lb * 1 lb b. Given 11.6 in. Need centimeters 2.54 cm Plan in. S cm 1 in. 2.54 cm = 29.5 cm (3 SFs) Set-up 11.6 in. * 1 in.

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Chemistry and Measurements

c. Given 0.15 qt Need milliliters 946 mL Plan qt S mL 1 qt 946 mL = 140 mL (2 SFs) Set-up 0.15 qt * 1 qt d. Given 35.41 kg Need pounds 2.20 lb Plan kg S lb 1 kg 2.20 lb = 77.9 lb (3 SFs) Set-up 35.41 kg * 1 kg 2.59 a. Given 175 cm Need meters 1m Plan cm S m 100 cm 1m = 1.75 m (3 SFs) Set-up 175 cm * 100 cm b. Given 5000 mL Need liters 1L Plan mL S L 1000 mL 1L = 5 L (1 SF) Set-up 5000 mL * 1000 mL c. Given 0.0055 kg Need grams 1000 g Plan kg S g 1 kg 1000 g Set-up 0.0055 kg * = 5.5 g (2 SFs) 1 kg d. Given 3500 cm3 Need liters 1 mL 1L Plan cm3 S mL S L 3 1000 mL 1 cm 1 mL 1L Set-up 3500 cm3 * * = 3.5 L (2 SFs) 3 1000 mL 1 cm 2.60 a. Given 800 mg Need grams 1g Plan mg S g 1000 mg 1g = 0.8 g (1 SF) Set-up 800 mg * 1000 mg b. Given 3.2 dL Need milliliters 100 mL Plan dL S mL 1 dL 100 mL = 320 mL (2 SFs) Set-up 3.2 dL * 1 dL c. Given 2840 mg Need grams 1g Plan mg S g 1000 mg 1g = 2.84 g (3 SFs) Set-up 2840 mg * 1000 mg

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Chapter 2

d. Given

0.29 kg Need grams 1000 g Plan kg S g 1 kg 1000 g Set-up 0.29 kg * = 290 g (2 SFs) 1 kg 2.61 a. Given

0.500 qt Need milliliters 946 mL Plan qt S mL 1 qt 946 mL = 473 mL (3 SFs) Set-up 0.500 qt * 1 qt b. Given 175 lb Need kilograms 1 kg Plan lb S kg 2.20 lb 1 kg Set-up 175 lb * = 79.5 kg (3 SFs) 2.20 lb c. Given 74 kg body mass, 15, body fat Need pounds of body fat Plan kg of body mass S kg of body fat S lb of body fat (percent equality: 100 kg of body mass = 15 g of body fat) 15 kg body fat 2.20 lb body fat 100 kg body mass 1 kg body fat 15 kg body fat 2.20 lb body fat Set-up 74 kg body mass * * 100 kg body mass 1 kg body fat = 24 lb of body fat (2 SFs) d. Given 10.0 oz of fertilizer, 15, nitrogen Need grams of nitrogen Plan oz of fertilizer S lb of fertilizer S g of fertilizer S g of nitrogen (percent equality: 100 g of fertilizer = 15 g of nitrogen) 1 lb 454 g 15 g nitrogen 16 oz 1 lb 100 g fertilizer Set-up

454 g fertilizer 15 g nitrogen 1 lb fertilizer * * 16 oz fertilizer 1 lb fertilizer 100 g fertilizer = 43 g of nitrogen (2 SFs)

10.0 oz fertilizer *

2.62 a. Given 0.750 L of wine, 12, alcohol Need milliliters of alcohol Plan L of wine S mL of wine S mL of alcohol (percent equality: 100 mL of wine = 12 mL of alcohol) 1000 mL wine 12 mL alcohol 1 L wine 100 mL wine 1000 mL wine 12 mL alcohol Set-up 0.750 L wine * * = 90. mL of alcohol (2 SFs) 1 L wine 100 mL wine b. Given 1 high-fiber muffin, 51, fiber, 6 muffins = 12 oz Need grams of fiber Plan number of muffins S oz S lb S g of muffin S g of fiber (percent equality: 100 g of fiber muffin = 51 g of fiber) 454 g 51 g fiber 12 oz 1 lb 6 muffins 16 oz 1 lb 100 g muffin 454 g 51 g fiber 12 oz 1 lb * * * = 29 g of fiber (2 SFs) 6 muffins 16 oz 1 lb 100 g muffin c. Given 1.43 kg of peanut butter, 8.0, of peanut butter/sandwich Need ounces of peanut butter/sandwich Set-up

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1 muffin *

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Chemistry and Measurements

g of peanut butter (pb) S lb of pb S oz of pb S oz of pb/sandwich k (percent equality: 100 oz of peanut butter = 8.0 oz of pb/sandwich) 2.20 lb 16 oz 8.0 oz pb/sandwich 1 kg 1 lb 100 oz pb 2.20 lb pb 16 oz pb 8.0 oz pb/sandwich Set-up 1.43 kg peanut butter * * * 1 kg pb 1 lb pb 100 oz pb = 4.0 oz of peanut butter/sandwich (2 SFs) d. Given 5.0 kg of pecans, 22.0, pecans Need pounds of chocolate bars Plan kg of pecans S kg of bars S lb of bars 100 kg choc. bars 2.20 lb (percent equality: 100 kg of bars = 22.0 kg of pecans) 22.0 kg pecans 1 kg 100 kg choc. bars 2.20 lb Set-up 5.0 kg pecans * * = 50. lb of chocolate bars (2 SFs) 22.0 kg pecans 1 kg Plan

2.63 a. Given

250 L of water Need gallons of water 1.06 qt 1 gal Plan L S qt S gal 1L 4 qt 1.06 qt 1 gal Set-up 250 L * * = 66 gal (2 SFs) 1L 4 qt b. Given 0.024 g of sulfa drug, 8-mg tablets Need number of tablets Plan g of sulfa drug S mg of sulfa drug S number of tablets 1000 mg 1 tablet 1g 8 mg sulfa drug 1000 mg 1 tablet Set-up 0.024 g sulfa drug * * = 3 tablets (1 SF) 1g 8 mg sulfa drug c. Given 34-lb child, 115 mg of ampicillin/kg of body mass Need milligrams of ampicillin Plan lb of body mass S kg of body mass S mg of ampicillin 1 kg 115 mg ampicillin 2.20 lb 1 kg body mass 1 kg body mass 115 mg ampicillin Set-up 34 lb body mass * * 2.20 lb body mass 1 kg body mass = 1800 mg of ampicillin (2 SFs) d. Given 4.0 oz of ointment Need grams of ointment 1 lb 454 g Plan oz S lb S g 16 oz 1 lb 454 g 1 lb * = 110 g of ointment (2 SFs) Set-up 4.0 oz * 16 oz 1 lb

2.64 a. Given 1 day, 1.0 g of tetracycline/6 h, 500-mg tablets Need number of tablets Plan days S hours S g of tetracycline S mg of tetracycline S number of tablets 1.0 g tetracycline 1000 mg 24 h 1 tablet 1 day 6h 1g 500 mg tetracycline Set-up 1.0 g tetracycline 1000 mg 24 h 1 tablet 1 day * * * * = 8 tablets (1 SF) 1 day 6h 1g 500 mg tetracycline b. Given 180-lb patient, 5.00 mg of medication/kg of body mass Need milligrams of medication Plan lb of body mass S kg of body mass S mg of medication 1 kg 5.00 mg medication 2.20 lb 1 kg body mass Copyright © 2019 Pearson Education, Inc.

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Chapter 2

1 kg body mass 5.00 mg medication * 2.20 lb body mass 1 kg body mass = 410 mg of medication (2 SFs) c. Given 0.50 mg of atropine, 0.10 mg of atropine/mL of solution Need milliliters of solution 1 mL solution Plan mg of atropine S mL of solution 0.10 mg atropine 1 mL solution Set-up 0.50 mg atropine * = 5.0 mL of solution (2 SFs) 0.10 mg atropine d. Given 5.0 pt of plasma Need milliliters of plasma 473 mL Plan pt S mL 1 pt 473 mL Set-up 5.0 pt * = 2400 mL of plasma (2 SFs) 1 pt Set-up

180 lb body mass *

2.65 a. Given 500. mL of IV saline solution, 80. mL/h Need infusion time in hours 1h Plan mL of IV saline solution S hours 80. mL saline solution 1h Set-up 500. mL saline solution * = 6.3 h (2 SFs) 80. mL saline solution b. Given 72.6-lb child, 1.5 mg of Medrol/kg of body mass, 20. mg of Medrol/mL of solution Need milliliters of Medrol solution Plan lb of body mass S kg of body mass S mg of Medrol S mL of solution 1 kg 1.5 mg Medrol 1 mL solution 2.20 lb 1 kg body mass 20. mg Medrol 1 kg body mass 1.5 mg Medrol 1 mL solution Set-up 72.6 lb body mass * * * 2.20 lb body mass 1 kg body mass 20. mg Medrol = 2.5 mL of Medrol solution (2 SFs) 2.66 a. Given o rdered dose 12.5 mg of promethazine, stock 25 mg of promethazine/mL of solution Need milliliters of promethazine solution 1 mL solution Plan mg of promethazine S mL of stock solution 25 mg promethazine 1 mL solution Set-up 12.5 mg promethazine * = 0.50 mL of stock solution (2 SFs) 25 mg promethazine b. Given 67-lb child, 25 mg of ampicillin/kg of body mass, 250 mg of ampicillin/capsule Need number of capsules Plan lb of body mass S kg of body mass S mg of ampicillin S number of capsules 1 kg body mass 25 mg ampicillin 1 capsule 2.20 lb body mass 1 kg body mass 250 mg ampicillin 1 kg body mass 25 mg ampicillin 1 capsule Set-up 67 lb body mass * * * 2.20 lb body mass 1 kg body mass 250 mg ampicillin = 3.0 capsules of ampicillin (2 SFs) mass (grams) 2.67 Density is the mass of a substance divided by its volume. Density = volume (mL) 3 The densities of solids and liquids are usually stated in g/mL or g/cm , so in some problems the units will need to be converted. mass (grams) 24.0 g = = 1.20 g/mL (3 SFs) a. Density = volume (mL) 20.0 mL b. Given 0.250 lb of butter, 130.3 mL Need density (g/mL)

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Chemistry and Measurements

454 g lb S g, then calculate density 1 lb 454 g Set-up 0.250 lb * = 113.5 g (3 SFs allowed) 1 lb 113.5 g mass 6 Density = = = 0.871 g/mL (3 SFs) volume 130.3 mL c. Given 12.00 mL initial volume, 13.45 mL final volume, 4.50 g Need density (g/mL) Plan calculate volume by difference, then calculate density Set-up volume of gem: 13.45 mL total - 12.00 mL water = 1.45 mL 4.50 g mass 6 Density = = = 3.10 g/mL (3 SFs) volume 1.45 mL 3.85 g mass d. Density = = = 1.28 g/mL (3 SFs) volume 3.00 mL Plan

155 g mass = = 1.24 g/mL (3 SFs) volume 125 mL 2.68 lb, 3.5 L Need density (g/mL)

2.68 a. Density = b. Given

454 g 1000 mL 1 lb 1L 454 g 1000 mL Set-up 2.68 lb * = 1220 g (3 SFs) and 3.5 L * = 3500 mL (2 SFs) 1 lb 1L 1220 g mass 6 Density = = = 0.35 g/mL (2 SFs) volume 3500 mL 4.004 g mass c. Density = = = 1.001 g/mL (4 SFs) volume 4.000 mL d. Given 1.65 lb, 170 mL Need density (g/mL) 454 g Plan lb S g, then calculate density 1 lb 454 g Set-up 1.65 lb * = 749 g (3 SFs) 1 lb 749 g mass 6 Density = = = 4.4 g/mL (2 SFs) volume 170 mL

Plan

lb S g

and

L S mL, then calculate density

2.69 a. Given 514.1 g, 114 cm3 Need density (g/mL) Plan convert volume cm3 S mL, then calculate density 1 mL Set-up 114 cm3 * = 114 mL 1 cm3 514.1 g mass 6 Density = = = 4.51 g/mL (3 SFs) volume 114 mL b. Given 0.100 pt, 115.25 g initial, 182.48 g final Need density (g/mL) Plan pt S mL, then calculate mass by difference, then calculate density 473 mL 1 pt 473 mL Set-up 0.100 pt * = 47.3 mL (3 SFs) 1 pt mass of syrup = 182.48 g - 115.25 g = 67.23 g 67.23 g mass 6 Density = = = 1.42 g/mL (3 SFs) volume 47.3 mL

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Chapter 2

c. Given 8.51 kg, 3.15 L Need Plan

kg S g

and

density (g/mL)

L S mL, then calculate density

1000 g 1 kg

1000 mL 1L

1000 g = 8510 g (3 SFs) and 1 kg 1000 mL 3.15 L * = 3150 mL (3 SFs) 1L 8510 g mass 6 Density = = = 2.70 g/mL (3 SFs) volume 3150 mL 2.70 a. Given 275 g, 207 cm3 Need density (g/mL) Plan convert volume cm3 S mL, then calculate density 1 mL Set-up 207 cm3 * = 207 mL 1 cm3 275 g mass = = 1.33 g/mL (3 SFs) 6 Density = volume 207 mL b. Given 0.104 kg, 14.3 cm3 Need density (g/mL) 1000 g 1 mL Plan kg S g and cm3 S mL, then calculate density 1 kg 1 cm3 1000 g 1 mL Set-up 0.104 kg * = 104 g (3 SFs) and 14.3 cm3 * = 14.3 mL (3 SFs) 1 kg 1 cm3 104 g mass 6 Density = = = 7.27 g/mL (3 SFs) volume 14.3 mL 43.5 g mass = = 0.791 g/mL (3 SFs) c. Density = volume 55.0 mL Set-up

8.51 kg *

2.71 In these problems, the density is used as a conversion factor. a. Given 1.50 kg of ethanol Need liters of ethanol 1000 g 1 mL 1L Plan kg S g S mL S L 1 kg 0.79 g 1000 mL 1000 g 1 mL 1L Set-up 1.50 kg alcohol * * * 1 kg alcohol 0.79 g 1000 mL = 1.9 L of ethanol (2 SFs) b. Given 6.5 mL of mercury Need grams of mercury 13.6 g Plan mL S g 1 mL 13.6 g = 88 g of mercury (2 SFs) Set-up 6.5 mL * 1 mL c. Given 225 cm3 of silver Need ounces of silver 1 mL 10.5 g 1 lb 16 oz Plan cm3 S mL S g S lb S oz 3 3 454 g 1 lb 1 cm 1 cm 10.5 g 1 mL 1 lb 16 oz * * * = 83.3 oz of silver (3 SFs) Set-up 225 cm3 * 3 1 mL 454 g 1 lb 1 cm 2.72 a. Given 18.0 mL of water, 35.6 g of silver Need final volume (mL) 1 mL Plan g S mL, then calculate the final volume using addition 10.5 g 1 mL = 3.39 mL of silver (3 SFs) Set-up 35.6 g * 10.5 g 18.0 mL water + 3.39 mL silver = 21.4 mL total volume (rounded to tenths)

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