Chapter 7: Gases, Liquids, Solids

Question 1

Kinetic Theory

Answer 1

Gases consist of tiny particles moving in rapid, random, straight-line motion until collision with each other or the walls of the container.

• collisions are perfectly elastic
• gas particles have mass but no volume
• distances between particles are very large compared to the size of particles themselves

Question 2

Physical properties of Gases

Answer 2

Expand to fill containers
rapid diffusion
form homogenous mixtures
compressible
exert pressure

Question 3

Diffusion

Answer 3

spreading of gas over a given time

due to random, rapid straight line motion until collision

Question 4

Compression

Answer 4

Gases can be compressed due to volume being negligible

Question 5

Gas Pressure

Answer 5

As particles move, they collide with walls = exert force
velocities of particles and frequency of collisions determine gas pressure

velocities of particles increase = pressure increase.
increase in number of particles= increase in pressure

Question 6

Pressure and Volume

Answer 6

Volume decrease, pressure increase

reduction of vol. = increase in collisions

Question 7

Pressure and Temp.

Answer 7

Increase temp = increase in pressure

particles have more K.E. therefore move faster therefore increase in collisions

Question 8

Avagadro’s Hypothesis

Answer 8

equal volume of gases at the same temperature and pressure contain equal numbers of particles
volume is proportional to amount of mole of gas present

Question 9

Liquid properties

Answer 9

particles in L are closer together than particles in Gases
Particles constantly change positions but can not travel far before collisions occur
lack of space between particles = incompressible
weak attractive forces

Question 10

Solid properties

Answer 10

Strong attractive forces
Particles close together
Particles vibrate in fix positions
Have definite shape and volume

Question 11

Changes in state

Answer 11

Pure substances undergo changes of state at definite temperatures
- During a phase change, the temperature of a substance remains constant because K.E. doesnt change, potential energy is changed.

Question 12

Evaporation

Answer 12

• change from liquid to gaseous state that occurs at a temperature below the liquids boiling point
• particles that have sufficient kinetic energy escape the attractive forces of their particles and become a gas
• due to the more energetic particles escaping, the average kinetic energy of the particles in the liquid falls
• temperature of a liquid drops as evaporation happens

Question 13

Vapour Pressure

Answer 13

Is a pressure exerted by vapour in equilibrium with its gas or liquid at a specific temperature in a closed system

• two things occurring: evaporation and condensation
• stronger attractive forces= greater K.E. required for particles to escape = lower V.P.
• Weaker attractive forces = less K.E. required for particles to escape = higher V.P.

Question 14

Boiling

Answer 14

occurs when vapour pressure = atmospheric pressure

low atmospheric pressure = low boiling point