Internal Energy and Heat Capacity

Question 1

What is internal energy?

Answer 1

The total energy stored by the particles making up a substance or system.

Question 2

When talking about internal energy, it is usually said to be made up of 2 parts. What are they?

Answer 2

Potential Energy Stores and Kinetic Energy Stores

Potential Energy Stores - Things like gravitational and elastic potential. They are not related to temperature.

Kinetic Energy Stores - The movement energy of the particles.

Question 3

When you heat up a substance, where does it transfer energy to?

Answer 3

The Kinetic Energy Store of all the particles

Therefore, it increases their internal energy. We measure this as an increase in temperature.

Question 4

What is temperature a measure of?

Answer 4

Temperature is a measure of the average internal energy of a substance.

The more internal energy a substance has, the higher its temperature will be.

Question 5

What is the specific heat capacity?

Answer 5

The amount of energy needed to raise the temperature of 1kg of a substance by 1°C.

It can also be thought of the amount of energy released as a substance cools.

Question 6

What is the equation for change in internal energy?

Answer 6

∆E = mc∆θ

Change in Internal Energy (Joules) = Mass (kg) x Specific Heat Capacity (J/kg°C) x Temperature Change (°C)

∆ = Change/Delta
θ = Theta, here meaning temperature

Question 7

What is the specific heat capacity of water?

Answer 7

4200J/kg°C