Physics 9702 · AS & A Level · The first law of thermodynamics
The first law of thermodynamics — practice question
An ideal gas with a fixed mass occupies a volume of $210\ \text{cm}^{3}$ at a pressure of $3.0 \times 10^{5}\ \text{Pa}$ and a temperature of $270\ \text{K}$. Its volume is then decreased, while the pressure stays constant, to $140\ \text{cm}^{3}$, as illustrated in Fig. 2.1. The gas’s final temperature is $T$.
(a(i))[3]
Determine the quantity of gas present.
(a(ii))[2]
Determine the gas’s final temperature, $T$.
(a(iii))[2]
Determine the external work done on the gas.
(b)[3]
For this alteration in the gas’s volume and temperature, $53\ \text{J}$ of thermal energy is transferred. Determine $\Delta U$, the change in internal energy of the gas.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The equation is $pV=nRT$.” …