Physics 9702 · AS & A Level · Kinetic theory of gases

Kinetic theory of gases — practice question

Smoke particles are kept suspended in stationary air. Brownian motion of the smoke particles is observed with a microscope.
(a(i))[1]

Describe what is observed through the microscope.

(a(ii))[2]

Describe how Brownian motion gives evidence for the nature of the movement of gas molecules.

(b(i))[3]

A fixed mass of an ideal gas has volume $2.40 \times 10^3\,\text{cm}^3$ at pressure $3.51 \times 10^5\,\text{Pa}$ and temperature $290\,\text{K}$. The gas is heated at constant volume until the temperature is $310\,\text{K}$ at pressure $3.75\times 10^5\,\text{Pa}$, as shown in Fig. 2.1. The thermal energy needed to increase the temperature of $1.00\,\text{mol}$ of the gas by $1.00\,\text{K}$ at constant volume is $12.5\,\text{J}$. Calculate, to three significant figures, the amount, in mol, of the gas.

(b(ii))[2]

Calculate the thermal energy transfer in the change.

(c(i))[1]

For the change in the gas in (b), state the amount of external work done on the gas.

(c(ii))[2]

For the change in the gas in (b), state the change in internal energy and the direction of the change.

Worked solution & mark scheme

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