Topic 3: Particle Model of Matter

Question 1

3.1

Answer 1

Changes of State and Particle Model

Question 2

State the different states of matter in order (least to most) of density of atoms.

Answer 2

• Gas
• Liquid
• Solid

Question 3

What is sublimation?

Answer 3

When a solid changes into a gas without passing through a liquid state.

Question 4

When water boils in an open pan, why does the mass of the pan of water appear to decrease?

Answer 4

Some of the water will evaporate and turn into water vapour. This will leave the pan meaning the mass of the pan will decrease. The mass of the whole system however remains constant.

Question 5

Explain the processes involved when a bathroom mirror mists up.

Answer 5

• Hot water evaporates to form water vapour
• This water vapour lands on the cooler mirror
• The vapour condenses and returns to liquid state on the mirror’s surface

Question 6

3.2

Answer 6

Internal Energy and Energy Transfers

Question 7

What is the internal energy of a substance?

Answer 7

• The energy stored by the particles
• The sum of the total kinetic and potential energies that make up the system

Question 8

How does heating affect the energy of a substance?

Answer 8

• Heating transfers energy to the substance
• It increases the energy of the particles that make up the substance

Question 9

What three factors determine the temperature change of a system?

Answer 9

1. Mass of substance being heated
2. Type of material (Specific Heat Capacity)
3. Energy inputted into the system

Question 10

What is the specific latent heat of fusion?

Answer 10

The energy required to change 1 kg of a substance from solid state to liquid state without a change in temperature.

Question 11

What is the specific latent heat of vaporisation?

Answer 11

The energy required to change 1 kg of a substance from liquid state to gas state (vapour) without a change in temperature.

Question 12

3.3

Answer 12

Particle Model and Pressure

Question 13

What factor affects the average kinetic energy of gas molecules?

Answer 13

• The temperature of the substance
• The higher the temperature, the higher the average kinetic energy of the molecules

Question 14

Explain how increasing the volume of a gas results in a decrease of pressure.

Answer 14

• Molecules become more spread out and so time between collisions increases
• This reduces the rate of collisions
• Rate of change of momentum decreases, and so force exerted on container decreases, resulting in a lower pressure

Question 15

Why does the temperature of air inside a bike pump increase when it is pumped?

Answer 15

• Work is done on a gas when it is compressed
• Doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules
• Temperature increases with an increase of average kinetic energy