Topic 3.2: Thermal Properties of Matter

Question 1

Define specific heat capacity

Answer 1

o SPECIFIC HEAT CAPACITY: The amount of thermal energy required to raise the temperature of 1kg of a substance by 1K

Question 2

Define thermal capacity

Answer 2

o THERMAL CAPACITY: The amount of thermal energy required to raise the temperature of an object by 1K.

Question 3

Define microscopic description

Answer 3

o MICROSCOPIC DESCRIPTION: Considers properties of matter at a particle level. Molecules are in motion and collide with each other and the container.

Question 4

Define kinetic energy of particles

Answer 4

o KINETIC ENERGY OF PARTICLES: Temperature is a measure of the average kinetic energy of the particles.

Question 5

• 3.2.3: Explain the physical difference between the solid, liquid, and gaseous phases in terms of molecular structure and particle motion

Answer 5

o PHASES OF MATTER: Particles in a solid are locked into the crystal structure and do not have enough KE to escape. In a liquid, they overcome the chemical bonds but cannot separate completely for the other atoms. The particles in a gas have enough KE to escape from each other.
o Solids –fixed positions, many strong bonds (potential energy)
o Liquids – Changing positions, many temporary bonds
o Gases – Free moving, no bonds

Question 6

What is the process of going from a gas to a solid?

Answer 6

deposition

Question 7

What is the process of going from a solid to a gas?

Answer 7

sublimination

Question 8

What is the process of going from a solid to a liquid?

Answer 8

melting

Question 9

What is the process of going from a liquid to a solid?

Answer 9

solidification

Question 10

What is the process of going from a liquid to a gas?

Answer 10

evaporation

Question 11

What is the process of going from a gas to a liquid?

Answer 11

condensation

Question 12

• 3.2.6: Distinguish between evaporation and boiling

Answer 12

o EVAPORATION: The process by which faster-moving molecules escape from the surface of a liquid. This results in a cooling of the liquid.
o BOILING: The process by which a liquid changes into a solid at the constant temperature of the boiling point.

Question 13

• 3.2.9: Define pressure and microscopic description of pressure

Answer 13

o PRESSURE: The force exerted per unit area. Measured in pascals.
o MICROSCOPIC DESCRIPTION OF PRESSURE: Many moving particles exert forces when they collide with container walls give the effect of pressure being exerted by the gas.

Question 14

Define ideal gas

Answer 14

o IDEAL GAS: A theoretical gas composed of a randomly moving non-interacting particles. It is a useful idea because many real gases behave like an ideal gas unless temperature or pressure are very high or low.

Question 15

• 3.2.10: State the assumptions of the kinetic model of an ideal gas (6)

Answer 15

o KINETIC MODEL OF AN IDEAL GAS: A model which treats a gas as many molecules subject to the following assumptions:
 The molecules obey Newton’s laws
 The intermolecular forces are negligible
 The molecules are spherical with negligible volume
 The motion of the molecules is random.
 The collisions are perfectly elastic.
 The time taken for a collision is negligible.

Question 16

What is temperature?

Answer 16

• 3.2.11: State that temperature is a measure of the average random kinetic energy of the molecules of an ideal gas
o KINETIC ENERGY OF PARTICLES: Temperature is a measure of the average random kinetic energy of the particles.