1.E: Exercises
 Page ID
 68024
These are homework exercises to accompany Chapter 1 of the Ball et al. "The Basics of GOB Chemistry" Textmap.
1.1: What Is Chemistry?
Exercises

Based on what you know, which fields are branches of science?
 meteorology (the study of weather)
 astrophysics (the physics of planets and stars)
 economics (the study of money and monetary systems)
 astrology (the prediction of human events based on planetary and star positions)
 political science (the study of politics)

Based on what you know, which fields are a branches of science?
 history (the study of past events)
 ornithology (the study of birds)
 paleontology (the study of fossils)
 zoology (the study of animals)
 phrenology (using the shape of the head to determine personal characteristics)

Which of the following are examples of matter?
 a baby
 an idea
 the Empire State Building
 an emotion
 the air
 Alpha Centauri, the closest known star (excluding the sun) to our solar system

Which of the following are examples of matter?
 your textbook
 brain cells
 love
 a can of soda
 breakfast cereal

Suggest a name for the science that studies the physics of rocks and the earth.

Suggest a name for the study of the physics of living organisms.

Engineering is the practical application of scientific principles and discoveries to develop things that make our lives easier. Is medicine science or engineering? Justify your answer.

Based on the definition of engineering in Exercise 7, would building a bridge over a river or road be considered science or engineering? Justify your answer.

When someone says, “I have a theory that excess salt causes high blood pressure,” does that person really have a theory? If it is not a theory, what is it?

When a person says, “My hypothesis is that excess calcium in the diet causes kidney stones,” what does the person need to do to determine if the hypothesis is correct?

Some people argue that many scientists accept many scientific principles on faith. Using what you know about the scientific method, how might you argue against that assertion?

Most students take multiple English classes in school. Does the study of English use the scientific method?
Answers

 science
 science
 not science
 not science
 not science

 matter
 not matter
 matter
 not matter
 matter
 matter

geophysics

Medicine is probably closer to a field of engineering than a field of science, but this may be arguable. Ask your doctor.
 In scientific terms, this person has a hypothesis.
 Science is based on reproducible facts, not blind belief.
1.2: The Classification of Matter
Exercises

Does each statement refer to a chemical property or a physical property?
 Balsa is a very light wood.
 If held in a flame, magnesium metal burns in air.
 Mercury has a density of 13.6 g/mL.
 Human blood is red.

Does each statement refer to a chemical property or a physical property?
 The elements sodium and chlorine can combine to make table salt.
 The metal tungsten does not melt until its temperature exceeds 3,000°C.
 The ingestion of ethyl alcohol can lead to disorientation and confusion.
 The boiling point of isopropyl alcohol, which is used to sterilize cuts and scrapes, is lower than the boiling point of water.

Define element. How does it differ from a compound?

Define compound. How does it differ from an element?

Give two examples of a heterogeneous mixture.

Give two examples of a homogeneous mixture.

Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.
 xenon, a substance that cannot be broken down into chemically simpler components
 blood, a substance composed of several types of cells suspended in a salty solution called plasma
 water, a substance composed of hydrogen and oxygen

Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.
 sugar, a substance composed of carbon, hydrogen, and oxygen
 hydrogen, the simplest chemical substance
 dirt, a combination of rocks and decaying plant matter

Identify each substance as an element, a compound, a heterogeneous mixture, or a solution.
 air, primarily a mixture of nitrogen and oxygen
 ringer’s lactate, a standard fluid used in medicine that contains salt, potassium, and lactate compounds all dissolved in sterile water
 tartaric acid, a substance composed of carbon, hydrogen, and oxygen

Identify each material as an element, a compound, a heterogeneous mixture, or a solution.
 equal portions of salt and sand placed in a beaker and shaken up
 a combination of beeswax dissolved in liquid hexane
 hydrogen peroxide, a substance composed of hydrogen and oxygen

What word describes each phase change?
 solid to liquid
 liquid to gas
 solid to gas

What word describes each phase change?
 liquid to solid
 gas to liquid
 gas to solid
Answers

 physical property
 chemical property
 physical property
 physical property

An element is a substance that cannot be broken down into chemically simpler components. Compounds can be broken down into simpler substances.

a salt and pepper mix and a bowl of cereal (answers will vary)

 element
 heterogeneous mixture
 compound

 solution
 solution
 compound

 melting or fusion
 boiling or evaporation
 sublimation
1.3: Measurements
Exercises

Why are both parts of a quantity important when describing it?

Why are measurements an important part of any branch of science, such as chemistry?

You ask a classmate how much homework your chemistry professor assigned. Your classmate answers, “twenty.” Is that a proper answer? Why or why not?

Identify the number and the unit in each quantity.
 five grandchildren
 16 candles
 four score and seven years
 40 days and 40 nights
 12.01 grams
 9.8 meters per second squared
 55 miles per hour
 98.6 degrees Fahrenheit
Answers

The number states how much, and the unit states of what. Without the number and the unit, a quantity cannot be properly communicated.

No, it is not a proper answer; you do not know whether the professor meant homework problem number 20 or 20 homework problems.
1.4: Expressing Numbers: Scientific Notation
Exercises

Why is scientific notation useful in expressing numbers?

What is the relationship between the power and the number of places a decimal point is moved when going from standard to scientific notation?

Express each number in scientific notation.
 0.00064
 5,230,000
 −56,200
 0.000000000220
 1.0

Express each number in scientific notation.
 678
 −1,061
 0.000560
 0.0000003003
 100,000,000

Express each number in standard form.
 6.72 × 10^{4}
 2.088 × 10^{−4}
 −3 × 10^{6}
 9.98 × 10^{−7}

Express each number in standard form.
 9.05 × 10^{5}
 1.0 × 10^{−3}
 6.022 × 10^{23}
 8.834 × 10^{−12}

Complete the following table:
Incorrect Scientific Notation Correct Scientific Notation 54.7 × 10^{4} 0.0066 × 10^{3} 3,078 × 10^{0} 
Complete the following table:
Incorrect Scientific Notation Correct Scientific Notation 234.0 × 10^{1} 36 × 10^{−4} 0.993 × 10^{5}
Answers

Scientific notation is more convenient than listing a large number of zeros.

 6.4 × 10^{−4}
 5.23 × 10^{6}
 −5.62 × 10^{4}
 2.20 × 10^{−10}
 1.0 × 10^{0}

 67,200
 0.0002088
 −3,000,000
 0.000000998

Incorrect Scientific Notation Correct Scientific Notation 54.7 × 10^{4} 5.47 × 10^{5} 0.0066 × 10^{3} 6.6 × 10^{0} 3,078 × 10^{0} 3.078 × 10^{3}
1.5: Expressing Numbers: Significant Figures
Exercises

Define significant figures. Why are they important?

Define the different types of zeros found in a number and explain whether or not they are significant.

How many significant figures are in each number?
 140
 0.009830
 15,050
 221,560,000
 5.67 × 10^{3}
 2.9600 × 10^{−5}

How many significant figures are in each number?
 1.05
 9,500
 0.0004505
 0.00045050
 7.210 × 10^{6}
 5.00 × 10^{−6}

Round each number to three significant figures.
 34,705
 34,750
 34,570

Round each number to four significant figures.
 34,705
 0.0054109
 8.90443 × 10^{8}

Perform each operation and express the answer to the correct number of significant figures.
 467.88 + 23.0 + 1,306 = ?
 10,075 + 5,822.09 − 34.0 = ?
 0.00565 + 0.002333 + 0.0991 = ?

Perform each operation and express the answer to the correct number of significant figures.
 0.9812 + 1.660 + 8.6502 = ?
 189 + 3,201.8 − 1,100 = ?
 675.0 − 24 + 1,190 = ?

Perform each operation and express the answer to the correct number of significant figures.
 439 × 8,767 = ?
 23.09 ÷ 13.009 = ?
 1.009 × 876 = ?

Perform each operation and express the answer to the correct number of significant figures.
 3.00 ÷ 1.9979 = ?
 2,300 × 185 = ?
 16.00 × 4.0 = ?

Use your calculator to solve each equation. Express each answer in proper scientific notation and with the proper number of significant figures. If you do not get the correct answers, you may not be entering scientific notation into your calculator properly, so ask your instructor for assistance.
 (5.6 × 10^{3}) × (9.04 × 10^{−7}) = ?
 (8.331 × 10^{−2}) × (2.45 × 10^{5}) = ?
 983.09 ÷ (5.390 × 10^{5}) = ?
 0.00432 ÷ (3.9001 × 10^{3}) = ?

Use your calculator to solve each equation. Express each answer in proper scientific notation and with the proper number of significant figures. If you do not get the correct answers, you may not be entering scientific notation into your calculator properly, so ask your instructor for assistance.
 (5.2 × 10^{6}) × (3.33 × 10^{−2}) = ?
 (7.108 × 10^{3}) × (9.994 × 10^{−5}) = ?
 (6.022 × 10^{7}) ÷ (1.381 × 10^{−8}) = ?
 (2.997 × 10^{8}) ÷ (1.58 × 10^{34}) = ?
Answers

Significant figures represent all the known digits plus the first estimated digit of a measurement; they are the only values worth reporting in a measurement.

 two
 four
 four
 five
 three
 five

 34,700
 34,800
 34,600

 1,797
 15,863
 0.1071

 3,850,000
 1.775
 884

 5.1 × 10^{−3}
 2.04 × 10^{4}
 1.824 × 10^{−3}
 1.11 × 10^{−6}
1.6: The International System of Units

List four base units.

List four derived units.

How many meters are in 1 km? How many centimeters are in 1 m?

How many grams are in 1 Mg? How many microliters are in 1 L?

Complete the following table:
Unit Abbreviation centiliter ms cm kL micrometer 
Complete the following table:
Unit Abbreviation microliter kilosecond dL ns millimeter 
What are some appropriate units for density?

A derived unit for velocity, which is the change of position with respect to time, is meters per second (m/s). Give three other derived units for velocity.
Answers

second, meter, kilogram, and kelvin (answers will vary)

1,000; 100

Unit Abbreviation centiliter cL millisecond ms centimeter cm kiloliter kL micrometer µm

grams per liter, grams per milliliter, and kilograms per liter (answers will vary)
1.7: Converting Units
Exercises

Give the two conversion factors you can construct using each pair of units.
 meters and kilometers
 liters and microliters
 seconds and milliseconds

Give the two conversion factors you can construct using each pair of units.
 grams and centigrams
 millimeters and meters
 liters and megaliters

How many meters are in 56.2 km?

How many seconds are in 209.7 ms?

How many microliters are in 44.1 L?

How many megagrams are in 90.532 g?

Convert 109.6 kg into micrograms. Express your final answer in scientific notation.

Convert 3.8 × 10^{5} mm into kilometers. Express your final answer in scientific notation.

Convert 3.009 × 10^{−5} ML into centiliters. Express your final answer in scientific notation.

Convert 99.04 dm into micrometers. Express your final answer in scientific notation.

The density of ethyl alcohol is 0.79 g/mL. What is the mass of 340 mL of ethyl alcohol?

The density of a certain fraction of crude oil is 1.209 g/mL. What is the mass of 13,500 mL of this fraction?

The density of ethyl alcohol is 0.79 g/mL. What is the volume of 340 g of ethyl alcohol?

The density of a certain component of crude oil is 1.209 g/mL. What is the volume of 13,500 g of this component?

Vitamin C tablets can come in 500 mg tablets. How many of these tablets are needed to obtain 10 g of vitamin C?

A tablet of penicillin contains 250 mg of the antibacterial drug. A prescription contains 44 tablets. What is the total mass of penicillin in the prescription?
Answers

 \(\mathrm{\dfrac{1,000\:m}{1\:km}\,;\:\dfrac{1\:km}{1,000\:m}}\)
 \(\mathrm{\dfrac{1,000,000\:\mu L}{1\:L}\,;\:\dfrac{1\:L}{1,000,000\:\mu L}}\)
 \(\mathrm{\dfrac{1,000\:ms}{1\:s}\,;\:\dfrac{1\:s}{1,000\:ms}}\)
 \(\mathrm{\dfrac{1,000\:m}{1\:km}\,;\:\dfrac{1\:km}{1,000\:m}}\)

5.62 × 10^{4} m

4.41 × 10^{7} µL

1.096 × 10^{11} µg

3.009 × 10^{3} cL

270 g

430 mL

20 tablets
1.8: Chapter Summary

A sample of urine has a density of 1.105 g/cm^{3}. What is the mass of 0.255 L of this urine?

The hardest bone in the body is tooth enamel, which has a density of 2.91 g/cm^{3}. What is the volume, in liters, of 75.9 g of tooth enamel?

Some brands of aspirin have 81 mg of aspirin in each tablet. If a person takes 8 tablets per day, how many grams of aspirin is that person consuming every day?

The US government has a recommended daily intake (RDI) of 5 µg of vitamin D per day. (The name recommended daily allowance was changed to RDI in 1997.) If milk contains 1.2 µg per 8 oz glass, how many ounces of milk are needed to supply the RDI of vitamin D?

The population of the United States, according to the 2000 census, was 281.4 million people.
 How many significant figures does this number have?
 What is the unit in this quantity?
 Express this quantity in proper scientific notation.

The United States produces 34,800,000,000 lb of sugar each year, and much of it is exported to other countries.
 How many significant figures does this number have?
 What is the unit in this quantity?
 Express this quantity in proper scientific notation.

Construct a conversion factor that can convert from one unit to the other in each pair of units.
 from millimeters to kilometers
 from kilograms to micrograms
 from centimeters to micrometers

Construct a conversion factor that can convert from one unit to the other in each pair of units.
 from kilometers to micrometers
 from decaliters to milliliters
 from megagrams to milligrams

What is the density of a dextrose solution if 355 mL of the solution has a mass of 406.9 g?

What is the density of a dental amalgam (an alloy used to fill cavities) if 1.005 kg of the material has a volume of 433 mL? Express your final answer in grams per milliliter.
For Exercises 11–16, see the accompanying table for the relationships between English and SI units.
1 m ≈ 39.36 in. ≈ 3.28 ft ≈ 1.09 yd 
1 cm ≈ 2.54 in. 
1 km ≈ 0.62 mi 
1 kg ≈ 2.20 lb 
1 lb ≈ 454 g 
1 L ≈ 1.06 qt 
1 qt ≈ 0.946 L 

Approximately how many inches are in 4.76 m?

Approximately how many liters are in 1 gal, which is exactly 4 qt?

Approximately how many kilograms are in a person who weighs 170 lb?

The average distance between Earth and the sun is 9.3 × 10^{7} mi. How many kilometers is that?

Show mathematically that 1 L equals 1 dm^{3}.

Show mathematically that 1 L equals 1,000 cm^{3}.
Answers

282 g

650 mg

 four significant figures
 people
 2.841 × 10^{8} people

 \(\mathrm{\dfrac{1\:km}{10^6\:mm}}\)
 \(\mathrm{\dfrac{10^9\:\mu g}{1\:kg}}\)
 \(\mathrm{\dfrac{10^4\:\mu m}{1\:cm}}\)
 \(\mathrm{\dfrac{1\:km}{10^6\:mm}}\)

1.15 g/mL

187 in.

77 kg

\(\mathrm{1\:L=0.001\:m^3\times\left(\dfrac{1\:dm}{0.1\:m}\right)^3=1\:dm^3}\)