Physics 9702 · AS & A Level · Equation of state

Equation of state — practice question

(a)[3]

State what the term ideal gas means.

(b)

Two cylinders A and B are linked by a tube of negligible volume, as shown in Fig. 2.1. At the start, tap T is closed. The cylinders contain an ideal gas at different pressures.

(b(i))[1]

Cylinder A has a fixed volume of $2.5 \times 10^3\,\text{cm}^3$ and contains gas at pressure $3.4 \times 10^5\,\text{Pa}$ and temperature $300\,\text{K}$. Show that cylinder A contains $0.34\,\text{mol}$ of gas.

(b(ii))[2]

Cylinder B has a fixed volume of $1.6 \times 10^3\,\text{cm}^3$ and contains $0.20\,\text{mol}$ of gas. After tap T is opened, the gas in both cylinders is at pressure $3.9 \times 10^5\,\text{Pa}$. No thermal energy enters or leaves the gas. Determine the final temperature of the gas.

(c)[3]

By referring to work done and the change in internal energy, suggest why the temperature of the gas in cylinder A has changed.

(ii)[2]

Cylinder B has a fixed volume of $1.6 \times 10^3\,\text{cm}^3$ and contains $0.20\,\text{mol}$ of gas. After tap T is opened, the gas pressure in both cylinders is $3.9 \times 10^5\,\text{Pa}$. No thermal energy enters or leaves the gas. Determine the final temperature of the gas.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: obeys equation $pV=\text{constant}\times T$ or $pV=nRT$

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