At the start, a sample of an ideal gas is in state A, with pressure $2.0 \times 10^5\,\text{Pa}$ and volume $0.016\,\text{m}^3$, as shown in Fig. 3.1.
In state A, the gas has temperature $400\,\text{K}$.
The gas then goes through two changes in sequence, X and Y.
For change X, the gas is heated at constant volume until the pressure becomes $4.0 \times 10^5\,\text{Pa}$. When X is complete, the gas is in state B.
For change Y, it then expands at constant temperature until its original pressure is reached again. When Y is complete, the gas is in state C.
(a)[2]
Explain, with reference to molecular kinetic energy and molecular potential energy, what is meant by the internal energy of an ideal gas.
(b(i))[2]
Determine the internal energy of the gas in state A.
(b(ii))[1]
Determine the gas temperature in state B.
(b(iii))[1]
Determine the gas volume in state C.
(b(iv))[3]
On Fig. 3.1, sketch the two changes, one for change X and one for change Y. Label the lines X and Y respectively.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “the total kinetic energy associated with the random motion of molecules” …