Internal Energy (CIE A Level Physics)

Define internal energy.

State and explain, in molecular terms, whether the internal energy of the following increases, decreases or does not change.
 

[3]

A monatomic gas, contained within a balloon, increases in temperature from 260 K to 310 K.

Calculate the factor by which the internal energy changes, stating whether this is an increase or decrease.

The initial internal energy was 2.3 kJ. The gas in the balloon is perfectly insulated.

[2]

[3]

State whether the balloon increases or decreases in size.

Explain your answer.

Describe and explain the change in average kinetic energy of the particles in this process.

A container of fixed volume holds 15.0 moles of a monatomic ideal gas. This is 9.03 × 10²⁴ atoms in total.

Each atom has a mass of 6.64 × 10⁻²⁷ kg. 

The gas is held at a temperature such that the root-mean-square speed is 1680 m s⁻¹.

Calculate this temperature.

The gas undergoes a process and now has a pressure of 150 kPa. The container has a fixed volume of 0.300 m³.

Calculate the new temperature of the gas.

For the process outlined in part (b):

[3]

[4]

The boiling point of this gas is 350 K. Explain why the potential energy of this ideal gas does not change.