Chapter 1—The Science of Chemistry



Chapter 1—The Science of Chemistry

MULTIPLE CHOICE

1. The state of matter in which a material has neither a definite shape nor a definite volume is the _____ state.

|a. |gaseous |c. |elemental |

|b. |liquid |d. |solid |

ANS: A PTS: 1 DIF: I OBJ: 1.1.2

2. Under ordinary conditions of temperature and pressure, the particles in a gas are

|a. |closely packed. |c. |held in fixed positions. |

|b. |very far from each other. |d. |unevenly distributed. |

ANS: B PTS: 1 DIF: I OBJ: 1.1.2

3. A chemical change occurs when

|a. |dissolved minerals solidify to form a crystal. |

|b. |ethanol is purified through distillation. |

|c. |salt deposits form from evaporated seawater. |

|d. |a leaf changes color. |

ANS: D PTS: 1 DIF: II OBJ: 1.1.3

4. A physical change occurs when a

|a. |peach spoils. |c. |bracelet turns your wrist green. |

|b. |copper bowl tarnishes. |d. |glue gun melts a glue stick. |

ANS: D PTS: 1 DIF: II OBJ: 1.1.3

5. Nitrogen monoxide and oxygen, both colorless gases, form a red-brown gas when mixed. Nitrogen monoxide and oxygen are called the

|a. |products. |c. |synthetics. |

|b. |equilibria. |d. |reactants. |

ANS: D PTS: 1 DIF: I OBJ: 1.1.4

6. Matter includes all of the following except

|a. |air. |c. |smoke. |

|b. |light. |d. |water vapor. |

ANS: B PTS: 1 DIF: II OBJ: 1.2.4

7. A measure of the quantity of matter is

|a. |density. |c. |volume. |

|b. |weight. |d. |mass. |

ANS: D PTS: 1 DIF: I OBJ: 1.2.1

8. A true statement about mass is that

|a. |mass is often measured with a spring scale. |

|b. |mass is expressed in pounds. |

|c. |as the force of Earth’s gravity on an object increases, the object’s mass increases. |

|d. |mass is determined by comparing the mass of an object with a set of standard masses that are part of a balance. |

ANS: D PTS: 1 DIF: I OBJ: 1.2.1

9. The liter is defined as

|a. |1000 m3. |c. |1000 g3. |

|b. |1000 cm3. |d. |1000 c3. |

ANS: B PTS: 1 DIF: I OBJ: 1.2.2

10. Quantitative observations are recorded using

|a. |numerical information. |c. |non-numerical information. |

|b. |a control. |d. |a system. |

ANS: A PTS: 1 DIF: I OBJ: 1.2.2

11. Which of the following does not describe a measurement standard?

|a. |Measurement standards avoid ambiguity. |

|b. |Measurement standards must be unchanging. |

|c. |A standard need not agree with a previously defined size. |

|d. |Confusion is eliminated when the correct measurement is applied. |

ANS: C PTS: 1 DIF: I OBJ: 1.2.2

12. Which of the following does not describe a unit?

|a. |A unit compares what is being measured with a previously defined size. |

|b. |A unit is usually preceded by a number. |

|c. |A unit is not needed to find a solution to a problem. |

|d. |The choice of unit depends on the quantity being measured. |

ANS: C PTS: 1 DIF: I OBJ: 1.2.2

13. All of the following are examples of units except

|a. |weight. |c. |gram. |

|b. |kilometer. |d. |teaspoon. |

ANS: A PTS: 1 DIF: I OBJ: 1.2.2

14. Which of the following is not an SI base unit?

|a. |kilogram |c. |liter |

|b. |second |d. |kelvin |

ANS: C PTS: 1 DIF: I OBJ: 1.2.2

15. The base unit for mass is the

|a. |gram. |c. |meter. |

|b. |cubic centimeter. |d. |kilogram. |

ANS: D PTS: 1 DIF: I OBJ: 1.2.2

16. The abbreviation that represents a volume unit is

|a. |mL. |c. |mm. |

|b. |mg. |d. |cm. |

ANS: A PTS: 1 DIF: I OBJ: 1.2.2

17. The SI base unit for time is the

|a. |day. |c. |minute. |

|b. |hour. |d. |second. |

ANS: D PTS: 1 DIF: I OBJ: 1.2.2

18. The metric unit for length that is closest to the thickness of a dime is the

|a. |micrometer. |c. |centimeter. |

|b. |millimeter. |d. |decimeter. |

ANS: B PTS: 1 DIF: II OBJ: 1.2.2

19. The abbreviation mm represents

|a. |micrometer. |c. |milliliter. |

|b. |millimeter. |d. |meter. |

ANS: B PTS: 1 DIF: I OBJ: 1.2.2

20. 1 cubic centimeter is equivalent to

|a. |1 milliliter. |c. |1 liter. |

|b. |1 gram. |d. |10–1 cubic decimeters. |

ANS: A PTS: 1 DIF: I OBJ: 1.2.2

21. The relationship between the mass m of a material, its volume V, and its density D is

|a. |V = mD. |c. |DV = m. |

|b. |Vm = D. |d. |D + V = m. |

ANS: C PTS: 1 DIF: I OBJ: 1.2.4

22. To calculate the density of an object,

|a. |multiply its mass and its volume. |c. |divide its volume by its mass. |

|b. |divide its mass by its volume. |d. |divide its mass by its area. |

ANS: B PTS: 1 DIF: I OBJ: 1.2.4

23. When density is measured,

|a. |a balance is always used. |

|b. |the units are always kg/m3. |

|c. |the temperature should be specified. |

|d. |the mass and volume do not need to be measured. |

ANS: C PTS: 1 DIF: I OBJ: 1.2.4

24. Electricity can convert oxygen into ozone. The ozone created by this process is

|a. |a new substance. |c. |a different state of oxygen. |

|b. |an isotope of oxygen. |d. |an allotrope of oxygen. |

ANS: D PTS: 1 DIF: I OBJ: 1.3.1

25. The only pure substance listed below is

|a. |bread dough. |c. |vitamin C (ascorbic acid). |

|b. |vinegar (5% acetic acid). |d. |seawater. |

ANS: C PTS: 1 DIF: II OBJ: 1.3.1

[pic]

26. The homogeneous mixture in the illustration above is in container

|a. |a. |c. |c. |

|b. |b. |d. |d. |

ANS: A PTS: 1 DIF: II OBJ: 1.3.3

27. A chemical formula for a molecular compound represents the composition of

|a. |a molecule. |c. |the ions that make up the compound. |

|b. |an atom. |d. |the crystal lattice. |

ANS: A PTS: 1 DIF: I OBJ: 1.3.1

[pic]

28. Which part of the illustration above shows the particles in a heterogeneous mixture?

|a. |a |c. |c |

|b. |b |d. |d |

ANS: A PTS: 1 DIF: II OBJ: 1.3.3

COMPLETION

1. The study of matter and changes that occur in matter best describes the science of ____________________.

ANS: chemistry

PTS: 1 DIF: I OBJ: 1.1.1

2. Any substance with a definite composition is a(n) ____________________.

ANS: chemical

PTS: 1 DIF: I OBJ: 1.1.1

3. Matter that has neither a definite volume nor a definite shape is in the ____________________ state.

ANS: gaseous

PTS: 1 DIF: I OBJ: 1.1.2

4. A sample of matter can be poured from container to container. It takes the shape of its container but only takes up a certain volume. Based on this information, the sample is in the ____________________ state.

ANS: liquid

PTS: 1 DIF: II OBJ: 1.1.2

5. The particles in a ____________________ are able to slide past each other.

ANS: liquid

PTS: 1 DIF: I

6. The melting of butter is a ____________________ change because it does not produce any new substances.

ANS: physical

PTS: 1 DIF: I OBJ: 1.1.3

7. An apple turning brown after being cut is an example of a ____________________ change.

ANS: chemical

PTS: 1 DIF: I OBJ: 1.1.3

8. The oxygen in air causes iron to rust. Iron and oxygen are ____________________ in thisprocess, and rust is a(n) ____________________.

ANS: reactants, product

PTS: 1 DIF: II OBJ: 1.1.4

9. The conversion factor used to change cg to g would be ____________________.

ANS: 1 g/100 cg

PTS: 1 DIF: I OBJ: 1.2.3

10. Two conversion factors that could be used together to change kilometers to millimeters would be ____________________ and ____________________.

ANS: 1000 m/1 km, 1000 mm/1 m

PTS: 1 DIF: II OBJ: 1.2.3

11. When examining a mineral, hardness and color are two of the properties used for identification. Hardness and color are examples of ____________________ properties.

ANS: physical

PTS: 1 DIF: I OBJ: 1.2.4

12. The two types of matter that are pure substances are ____________________ and ____________________.

ANS: elements, compounds

PTS: 1 DIF: I OBJ: 1.3.2

13. An alloy such as bronze is an example of a(n) ____________________ mixture.

ANS: homogeneous

PTS: 1 DIF: I OBJ: 1.3.3

14. Gravel is an example of a(n) ____________________ mixture.

ANS: heterogeneous

PTS: 1 DIF: I OBJ: 1.3.3

15. Iron and sulfur, when heated, form an iron sulfide that has different properties from either iron or sulfur. This iron sulfide is an example of a(n) ____________________.

ANS: compound

PTS: 1 DIF: I OBJ: 1.3.4

16. Some iron and some sulfur are mixed together then gently heated. When the result is cooled, the iron can be separated from the sulfur by using a magnet. This result is a(n) _________________________.

ANS: heterogeneous mixture

PTS: 1 DIF: II OBJ: 1.3.4

Use a periodic table to answer the following questions.

17. Use the periodic table to write the name for the element that has the symbol Pb. ____________________

ANS: lead

PTS: 1 DIF: I OBJ: 1.3.1

18. Use the periodic table to write the name for the element that has the symbol Mg. ____________________

ANS: magnesium

PTS: 1 DIF: I OBJ: 1.3.1

19. Use the periodic table to write the name for the element that has the symbol H. ____________________

ANS: hydrogen

PTS: 1 DIF: I OBJ: 1.3.1

20. Use the periodic table to write the name for the element that has the symbol P. ____________________

ANS: phosphorus

PTS: 1 DIF: I OBJ: 1.3.1

21. Use the periodic table to write the name for the element that has the symbol Al. ____________________

ANS: aluminum

PTS: 1 DIF: I OBJ: 1.3.1

22. Use the periodic table to write the name for the element that has the symbol Bi. ____________________

ANS: bismuth

PTS: 1 DIF: I OBJ: 1.3.1

23. Use the periodic table to write the symbol for the element helium. ____________________

ANS: He

PTS: 1 DIF: I OBJ: 1.3.1

24. Use the periodic table to write the symbol for the element tin. ____________________

ANS: Sn

PTS: 1 DIF: I OBJ: 1.3.1

25. Use the periodic table to write the symbol for the element neon. ____________________

ANS: Ne

PTS: 1 DIF: I OBJ: 1.3.1

26. Use the periodic table to write the symbol for the element chlorine. ____________________

ANS: Cl

PTS: 1 DIF: I OBJ: 1.3.1

27. Use the periodic table to write the symbol for the element iodine. ____________________

ANS: I

PTS: 1 DIF: I OBJ: 1.3.1

28. Use the periodic table to write the symbol for the element argon. ____________________

ANS: Ar

PTS: 1 DIF: I OBJ: 1.3.1

SHORT ANSWER

1. Explain why it is incorrect to assume that all chemicals are potentially dangerous or hazardous. Give two examples of chemicals that are necessary for human life.

ANS:

A chemical is any substance that has a definite composition. Some substances that have a definite composition are potentially hazardous, but most are not. Examples of necessary chemicals might include carbon dioxide, water, and oxygen.

PTS: 1 DIF: II OBJ: 1.1.1

2. Why can a gas fill the entire volume of its container?

ANS:

Gas particles have little attraction for each other and can easily and quickly move from one place to another.

PTS: 1 DIF: I OBJ: 1.1.2

3. In one experiment, magnesium metal melts. In a second experiment, magnesium metal ignites as it combines with oxygen. Classify the change in each experiment as chemical or physical. Explain your reasoning.

ANS:

In the first experiment, a physical change occurred. The chemical properties of magnesium were unchanged. In the second experiment, a chemical change occurred. A new substance with its own chemical properties was formed.

PTS: 1 DIF: II OBJ: 1.1.3

4. Differentiate between the reactants and the products in the reaction: copper plus water yields copper(II) oxide plus hydrogen.

ANS:

A reactant is an original substance, such as copper and water. A product is a resulting substance, such as copper(II) oxide and hydrogen.

PTS: 1 DIF: I OBJ: 1.1.4

5. When water boils, steam forms. When vinegar and baking soda combine, carbon dioxide gas is released. Which change is physical, and which is chemical? How do you know?

ANS:

In both changes, a gas is produced. However, water boiling is a physical change because no new products are produced; steam is still water. In the chemical change, a new product–carbon dioxide–is formed.

PTS: 1 DIF: II OBJ: 1.1.5

6. Distinguish between mass and weight.

ANS:

Mass is the amount of matter in something. Weight depends on Earth’s gravitational attraction on the object.

PTS: 1 DIF: II OBJ: 1.2.1

7. What are the SI standard units for length and mass? Why isn’t there a standard SI unit for volume?

ANS:

Meter and kilogram are the standard units for length and mass. Volume is a derived unit. It is calculated from length measurements, so it doesn’t have a standard SI unit.

PTS: 1 DIF: II OBJ: 1.2.2

8. Which one of the following is not an SI unit for density—kg/m3, g/cm3, g/mL, or g/m2? Explain your answer.

ANS:

The unit g/m2 is not a unit of density. Density units must express mass per volume. The unit m2 is a unit of area, not volume.

PTS: 1 DIF: II OBJ: 1.2.2

9. State which one of the following observations is quantitative and explain why it is.

a. The liquid turns blue litmus paper red.

b. The liquid boils at 100°C.

c. The liquid tastes bitter.

d. The liquid is cloudy.

ANS:

Answer b is quantitative because it involves a measured quantity. The other choices involve properties that are not quantitatively measured.

PTS: 1 DIF: II OBJ: 1.2.2

10. You make road signs, and you need a sign that shows a distance in both miles and km. Explain how you would determine the number of km you would show on the sign if you know the number of miles.

ANS:

Answers can vary but might include the following. Find the number of km per mile, and multiply by this conversion factor to change miles to km. You could also use conversion factors to change from miles to meters and from meters to kilometers.

PTS: 1 DIF: II OBJ: 1.2.3

11. Describe what lab equipment you might need to determine the density of a sample that is in the form of a cube. The material in the sample does not dissolve in water.

ANS:

You need lab equipment that will enable you to determine the mass and the volume of the cube. Use a balance to measure mass. You could use a ruler to measure dimensions and calculate volume, or you could use a graduated container and measure the volume of the cube by placing water in the container and subtracting the initial volume of the water from the volume of the water and the cube together.

PTS: 1 DIF: II OBJ: 1.2.4

12. Explain why flammability and combustibility are chemical properties.

ANS:

To observe either flammability or combustibility, a chemical change must occur. To observe either of these properties, something must burn and change to combustion products, such as water and carbon dioxide.

PTS: 1 DIF: II OBJ: 1.2.5

13. What are allotropes? Give an example of allotropes of an element.

ANS:

Allotropes are different molecular forms of the same element in the same physical state. Examples might include O2 and ozone, diamond and graphite, or the various forms of phosphorus.

PTS: 1 DIF: II OBJ: 1.3.1

14. Explain the difference between a pure substance and a homogeneous mixture. Use an example in your explanation.

ANS:

A homogeneous mixture can be separated by physical means, whereas a pure substance cannot. For example, salt can be removed from a salt-water mixture by evaporating the water, but to separate water into hydrogen and oxygen requires chemical means.

PTS: 1 DIF: II OBJ: 1.3.2

15. Name three different ways that mixtures can be separated.

ANS:

Any logical physical means of separation can be accepted. Answers might include filtration, distillation, decanting, sorting, evaporation, or use of a sieve.

PTS: 1 DIF: I OBJ: 1.3.4

PROBLEM

1. A section of highway is 5.82 km long. How long is this distance in meters?

ANS:

5.82 km × 1000 m/1 km = 5820 m

PTS: 1 DIF: I OBJ: 1.2.3

2. Each side of a cube is 42.6 mm long. What is the volume of the cube in cm3? Hint: Volume of a cube is calculated by (length of side)3.

ANS:

42.6 mm × 1 cm/10 mm = 4.26 cm

volume = (4.26 cm)3 = 77.3 cm3

PTS: 1 DIF: I OBJ: 1.2.3

3. For a certain map, the scale shows that 1 cm on the map equals 2.50 km on Earth’s surface. Two towns on the map are 4.75 cm apart. What is the actual distance between the two towns?

ANS:

4.75 cm 2.50 km/1 cm = 11.9 km

PTS: 1 DIF: II OBJ: 1.2.3

4. The density of aluminum is 2.70 g/cm3. The volume of a solid piece of aluminum is 1.50 cm3. Calculate its mass.

ANS:

m = DV = 2.70 g/cm3 × 1.50 cm3 = 4.05 g

PTS: 1 DIF: II OBJ: 1.2.4

5. The mass of a 5.00 cm3 sample of gold is 96.5 g. Calculate its density.

ANS:

D = m/V = 96.5 g/5.00 cm3 = 19.3 g/cm3

PTS: 1 DIF: II OBJ: 1.2.4

6. The density of pure diamond is 3.5 g/cm3. The mass of a diamond is 0.25 g. Calculate its volume.

ANS:

V = m/D = 0.25 g/3.5 g/cm3 = 0.071 cm3

PTS: 1 DIF: III OBJ: 1.2.4

ESSAY

1. Describe five ways in which chemistry is a part of your daily life.

ANS:

Answers will vary but might include specific chemical reactions in the human body, materials that are made through chemical processes, changes of state, or common chemical changes, such as burning or rotting.

PTS: 1 DIF: I OBJ: 1.1.1

2. Compare and contrast solids, liquids, and gases by explaining the behavior of their particles. Draw models to illustrate your answer.

ANS:

The arrangement of the particles in the three states accounts for their different properties. Particles in a solid move very little; particles in a liquid move more; and gas particles move the most. In the drawn models, particles in solids should appear closely packed and structured; particles in liquids should appear able to flow randomly past one another; and particles in gases should appear sparsely and randomly spaced.

PTS: 1 DIF: III OBJ: 1.1.2

3. Explain the similarities and differences in the information shown in a molecular formula and a structural formula for the same substance.

ANS:

Both formulas show the elements that make up the substance. The molecular formula shows only the composition. The structural formula shows both the composition and how the elements are arranged.

PTS: 1 DIF: II OBJ: 1.1.3

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