4.3.2 Internal energy and energy transfers

Question 1

What is the internal energy of a substance?

Answer 1

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

Question 2

How does heating affect the energy of a substance?

Answer 2

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

Question 3

What two things can heating a substance do?

Answer 3

1. Raise its temperature
2. Change the state of the substance

Question 4

What three factors determine the temperature change of a system?

Answer 4

1. Mass of substance being heated
2. Type of material (specific heat capacity)
3. Energy inputted into the system

Question 5

Define specific heat capacity

Answer 5

The amount of energy needed to increase the temperature of 1kg of a substance by 1 degree Celsius

Question 6

Describe how the internal energy and temperature of a substance changes when a change of state occurs

Answer 6

• The internal energy of the substance will be increased or decreased.
• The temperature of the substance will remain constant.

Question 7

Define specific latent heat

Answer 7

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

Question 8

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

Answer 8

Energy to change state = Mass x specific latent heat
- Energy ( j ), Mass (kg), specific latent heat ( j/kg )

Question 9

What is the specific latent heat of fusion?

Answer 9

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

Question 10

What is specific latent heat of vaporisation?

Answer 10

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