Chapter 11: The Gas State and Gas Laws
Mini Investigation: Inflating Experience, page 515
Answers may vary. Sample answers:
A. The air in the bottle that surrounds the balloon exerts pressure on the balloon making it more
difficult to inflate.
B. Piercing the plastic bottle allowed some of the air inside the bottle to escape as the balloon
was inflated. This decreased the air pressure acting on the balloon thereby making it easier to
inflate.
Section 11.1: States of Matter and the Kinetic Molecular Theory
Section 11.1 Questions, page 519
1. Solids have definite shape and volume because of strong forces of attraction between entities.
2. Gases have the largest space between entities and the weakest forces between entities. This
makes gases easy to compress. Solids have strong forces between entities. Solids are difficult to
compress because strong forces exist between entities, making the entities already very close
together.
3. From least ordered to most ordered, the states of matter are: gas, liquid, solid. The order of
states is related to the attractive forces between entities for each state. The greater the attractive
forces between entities, the greater the order in a particular state.
4. The attractive forces are greatest in solids. This prevents entities from moving past each other,
so no flow is possible. In liquids and gases, entities can flow past one another because attractive
forces are not as strong as those forces seen in solids.
5. (a) The kinetic molecular theory states that all substances contain entities that are in constant,
random motion.
(b) Figure 5 illustrates evaporation, which is the transition of a substance from a liquid to a gas
phase. As the liquid entities gain energy, they will eventually possess enough energy to break the
intermolecular forces of attraction in the liquid and escape, becoming a gas.
(c) The perfume moves from your body as a gas through the air. In cool temperatures, there is
less thermal energy for gas entities. The motion of gases including perfume entities is slower.
The slower the motion, the slower the perfume will spread throughout an area. In warmer
temperatures, the perfume entities move faster. Therefore the perfume will move faster through
the air in the summer because of increased temperature or thermal energy to the gas entities.
6. (a) As temperature increases, the motion of the entities increases.
(b) Kinetic energy is the energy of motion. Heating transfers energy to entities, which will
increase the motion of the entities, thereby increasing their kinetic energy. Temperature is a
measure of the average kinetic energy. As entities are heated, their motion increases and their
average kinetic energy (temperature) also increases.
7. As liquid nitrogen cools, the speed of the molecules is reduced. As the molecules slow down,
they interact with each other. Since nitrogen molecules are non-polar, the attractions between
molecules are only London dispersion forces. As the temperature continues to cool, the motion
of the molecules continues to slow and there is increased interaction or attraction between
nitrogen molecules until the nitrogen forms a solid.
8. Propane is a liquid under pressure. When this pressure is reduced (as the propane is released
into the air) the entities of propane will move farther apart, increasing the volume they occupy.
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Chapter 11: The Gas State and Gas Laws
11.1-1
When the entities move farther apart they will have fewer forces of attraction and they transition
from a liquid state into a gas state.
9. The objects in a room and the air in the room are close to room temperature, which is near
25 °C. Dry ice sublimates at a temperature of –78.5 °C. The dry ice will absorb thermal energy
from any object in the room that it has contact with the air in the room. This absorbed energy
gets converted to kinetic energy which will cause the carbon dioxide molecules to move more
quickly. As the molecules of the carbon dioxide move more quickly they will overcome the
forces of attraction and transition into the gas state.
10. (a) The particles of smoke move through the air randomly. If there is no wind, the smoke
particles collide with entities in the air and move outward from the smoke stack in all directions.
(b) The dispersion of smoke particles would be faster in summer. With higher temperatures in
the summer entities move faster. This increases the rate of collisions and causes the smoke to
disperse faster.
11. Brakes rely on the compressibility of the fluid in the brake lines to stop the car. Air has
greater compressibility compared to the liquid in the brake lines. The driver will have to apply
more pressure to cause the brakes to function if there is air present.
12. (a) Answers may vary. Sample answer: Liquid oxygen is obtained from liquefied air. Air is
liquefied by a rapid expansion under very high pressures. The liquid air is purified to remove
carbon dioxide and other substances. Then it undergoes fractional distillation to isolate the liquid
oxygen.
(b) Answers may vary. Sample answer: One medical use of liquid oxygen is that it can be stored
and transported as a liquid and then restored to gas form and given to patients with respiratory
difficulties. One industrial use of liquid oxygen is that it can be used as an oxidizer for rocket
fuel for space shuttles and for rocket propulsion.
Copyright © 2011 Nelson Education Ltd.
Chapter 11: The Gas State and Gas Laws
11.1-2