P1.2 Changes Of State

Question 1

What are the 5 main ways that a substance can change state?

Answer 1

• Melt
• Freeze
• Evaporate
• Condense
• Sublimate

Question 2

What is sublimation?

Answer 2

When a substance transitions from a solid to a gas without transitioning into a liquid in between

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 change is reversed.

Question 5

What 2 things can heating a substance do?

Answer 5

• Raise its temperature

- 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 degree Celsius.

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