Question

Pressure versus volume graphs for a real gas and an ideal gas are shown in the given figure. Answer the following questions on the basis of this graph.



A) Interpret the behaviour of real gas with respect to ideal gas at low pressure.

B) Interpret the behaviour of real gas with respect to ideal gas at high pressure.

C) Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas

Answer 1

A)
At low pressure, the curve of an ideal gas (red curve) and real gas (blue curve) are approaching each other.


This shows that at low pressure, the real gases show a very small deviation from ideal behaviour.
Also, the volume of real gas at low pressure is observed to be slightly lower than the ideal gas. It occurs due to the intermolecular forces of attraction which are present in a real gas.

B)
At high pressure, the ideal gas and real gas curves are going away from each other. This shows that there is a large deviation between real gas and ideal gas at high pressure.


This is because a real gas has a finite volume of molecules and at high pressure when the molecules come very close to each other they start repelling each other. Thus, volume of real gas observed to be higher than ideal gas at high pressure.

C)
At point A, where two curves intersect each other, the real gas behaves as ideal gas, which correspond to pressure $\left(P_1\right)$ and volume $\left(V_1\right).$