Chapter 1 Formative Answer Section
MATCHING
1. ANS:
2. ANS:
3. ANS:
4. ANS:
5. ANS:
6. ANS:
7. ANS:
8. ANS:
9. ANS:
10. ANS:
11. ANS:
12. ANS:
F
A
C
E
B
D
B
F
A
E
D
C
MULTIPLE CHOICE
1. ANS: B
2. ANS: C
3. ANS: B
4. ANS: B
5. ANS: D
6. ANS: D
7. ANS: D
8. ANS: B
9. ANS: B
10. ANS: D
11. ANS: D
12. ANS: A
13. ANS: D
14. ANS: B
15. ANS: D
16. ANS D
17. ANS E
18. ANS B
19. ANS B
20. ANS D
1. Problem
A physical change is a change that causes a physical property to change but there is no change in the
composition of the substance. A chemical change is a change in which there is a change in the
composition of a substance. Using these criteria, the answers are as follows.
(a) physical
(b) chemical
(c) physical
(d) chemical
(e) physical
(f) chemical
2. Problem
State whether each of the following sentences describes a chemical property or a physical property.
(a) Solid potassium permanganate, KMnO4(s), exists at room temperature as purple crystals.
(b) Gold can be hammered into thin sheets (it is malleable) and drawn into thin wires (it is ductile).
(c) Sodium metal reacts with water to form dissolved sodium hydroxide, NaOH(aq), and hydrogen
gas, H2(aq)
(d) Solid sodium chloride, NaCl(s), does not conduct electricity.
(e) Magnesium, Mg(s), burns in air with a bright, white flame.
(f) Ammonia, NH3, has a strong distinct odour.
Solution
A physical property is a property that you can observe without changing one substance into a
different substance. A chemical property is a property that you can observe when a substance is
converted into a different substance or substances.
(a) physical
(b) physical
(c) chemical
(d) physical
(e) chemical
(f) physical
3. Problem
Classify the following observations about the physical properties of diamond as qualitative or
quantitative.
(a) At room temperature, diamond is a clear, colourless, crystalline solid.
(b) Diamond has no odour.
(c) Diamond melts at 3800 K.
(d) Diamond has a density 0f 3.51 g/cm3.
(e) Diamond is neither malleable nor ductile.
Solution
Qualitative properties are properties that describe matter without using a measured quantity or
numerical expression. Quantitative properties are properties that can be measured and expressed
numerically.
(a) qualitative
(b) qualitative
(c) quantitative
(d) quantitative
(e) qualitative
4. Problem
The hardness of a substance is sometimes expressed numerically to Moh’s scale. Classify each of the
following statements about the hardness of diamond as qualitative or quantitative.
(a) Diamond has a hardness of 10.0 on Moh’s scale.
(b) Diamond is one of the hardest substances known to science.
Solution
Qualitative properties are properties that describe matter without using a measured quantity or
numerical expression. Quantitative properties are properties that can be measured and expressed
numerically.
(a) quantitative
(b) qualitative
5. Problem
Classify each situation as either a physical change or a chemical change. Explain
your reasoning.
(a) A rose bush grows from a seed that you have planted and nourished.
(b) A green coating forms on a copper statue when the statue is exposed to air.
(c) Your sweat evaporates to help balance your body temperature.
(d) Frost forms on the inside of a freezer.
(e) Salt is added to clear chicken broth.
(f) Your body breaks down the food you eat to provide energy for your body’s cells.
Plan Your Strategy
A physical change is a change that only affects the substance’s appearance, but not its chemical
composition. A chemical change will affect both the appearance and chemical composition of the
substance.
Act on Your Strategy
(a) “A rose bush grows from a seed that you have planted and nourished.” This is a chemical change
as different compounds are produced and the change cannot be reversed.
(b) “A copper statue forms a green coating when exposed to air.” This is a chemical change which is
the result of the copper oxidizing slowly in air in the presence of CO2 to produce Cu2(OH)2CO3,
which is a green substance.
The outer surface of the Statue of Liberty is made of copper, and this compound is what gives it its
green colour.
(c) “Your sweat evaporates to help keep your body temperature within a normal range.” Sweat
evaporating is a physical change. The water in sweat is just changing state from liquid to gas.
(d) “Frost forms on the inside of a freezer.” Frost forming in the freezer is the result of water vapour
in the air subliming (turning from gas directly to solid) to form ice on the walls of the freezer.
Sublimation is a physical change.
(e) “You add salt to clear chicken broth.” The added salt will dissolve, which is a physical change.
(f) “Your body breaks down the food you eat to provide energy for your body’s cells.” This is
definitely a chemical change as the broken down food cannot be converted back to its original form
in the body. Chemical breakdown of food is the main power source for the human body.
6. Problem
(a) chemical (b) physical (c) physical (d) chemical
7. Problem
(a) solubility physical (b) magnetic physical (c) sublimation physical (d) decomposition chemical
8. Problem
(a) chemical (b) physical (c) physical (d) physical
ESSAY
36. ANS:
A solution is a mixture that has a uniform composition. The composition of a heterogeneous mixture
is not uniform throughout. All solutions are mixtures, but not all mixtures are solutions. Salt water is
a solution; sand in water is a heterogeneous mixture.
37. ANS:
One example would be a solution of salt in water. The salt and water can be separated by distillation.
Another example would be a mixture of iron and sulfur, which can be separated by using a magnet
to attract the iron.
38. ANS:
An element is the simplest form of matter that has a unique set of properties. A compound is a
substance that contains two or more elements chemically combined in a fixed proportion. An
element cannot be broken down into simpler components through chemical reactions. Compounds
are substances that can be broken down into simpler substances through chemical reactions.
39. ANS:
Chemical properties describe the ability of a substance to undergo particular chemical changes.
Chemical properties can only be observed when a substance undergoes a change in composition.
Physical properties can be observed without altering the composition of a substance. The ability of
iron to rust is a chemical property of iron. The fact that iron is a solid at room temperature is a
physical property of iron.
40. ANS:
Physical changes do not alter the composition of a substance, but chemical changes do. When water
is boiled, the resulting gas is still water. However, when water is broken down into hydrogen and
oxygen in a chemical reaction, the water no longer exists. The latter is a chemical change; the former
a physical change.
41. ANS:
The law of conservation of mass states that in any physical change or chemical reaction, mass is
neither created nor destroyed. According to this law, the total mass the products in the
decomposition of water would be 10 grams. The total mass of the products would be the same mass
as the total mass of the reactants.
42. ANS:
Mass is a measure of the quantity of matter in an object. Weight is a measure of the strength of the
pull of a gravitational force (usually Earth's) on an object. The weight of an object changes,
however, with the object's distance from the center of the gravitational field it is in. The mass of a
person is exactly the same whether the person is on Earth or on the moon. The weight of that person
will be much less on the moon than on Earth because the gravitational pull of the moon is much less
than that of Earth.
43. ANS:
The student should infer that this is because a substance's atoms or molecules tend to move farther
apart with an increase in temperature. Consequently, the volume of the substance increases. There is
no change in the mass of the substance, however, and therefore the density (mass/volume) decreases.