P1.2 Changes of State

Question 1

What are the 5 main ways that a substance changes state?

Answer 1

1. Melt
2. Freeze
3. Evapourate
4. Sublimate
5. Condense

Question 2

What is sublimation?

Answer 2

When a Solid transitions straight to a Gas without transitioning into a liquid first

Question 3

What is always conserved when a substance changes state?

Answer 3

Mass

Question 4

How does a change of state differ from a chemical change?

Answer 4

In a change of state, the material can return to having its previous properties if the change is reversed.

Question 5

What two things can heating a substance do?

Answer 5

1. Raise it’s temperature

2. Change the state of the substance

Question 6

Define Specific Heat Capacity.

Answer 6

The amount of energy needed to increase the temperature of 1kg of a substance by 1 degrees Celcius

Question 7

What can be said about a material if it has a higher specific heat capacity?

Answer 7

For a constant mass, the material will need more energy to achieve a given temperature change.

Question 8

Define Specific Latent Heat.

Answer 8

The amount of energy needed to change the state of 1kg of a substance with no change in temperature

Question 9

State the equation for the energy required to change state. Give appropriate units.

Answer 9

• E = mL
• Energy to change state = mass x specific Latent heat
• Energy (J), Mass (kg), Specific Latent Heat (J/kg)

Question 10

What is the internal energy of a substance?

Answer 10

• The energy stored by the particles

- The sum of the total kinetic and potential energies that make up the system