Question

In the van der Waals equation given below, $(p + \dfrac{{an}}{{{V^2}}})(V - nb) = nRT$, then $\dfrac{{an}}{{{V^2}}}$ and $nb$ terms represent, respectively, corrections for:
A. derivations in the pressure and the temperature.
B. intermolecular attractive forces and molecular volumes.
C. intermolecular attractive forces and inelastic collisions.
D. intermolecular repulsive forces and high temperature.

Answer 1

Van der Waal corrected the ideal gas equation and added some changes in the pressure and volume parameters. According to him, the individual molecules of any gas occupy some volume of the container and put some pressure on the walls of the container and cannot be considered negligible.

Complete step by step answer:
According to the Van der Waals equation of gases:
$(p + \dfrac{{an}}{{{V^2}}})(V - nb) = nRT$
In the above equation, there are two corrections.
(i) Pressure correction: In this type of modification, Van der Waal considered the fact that the molecules interact with each other and have some intermolecular force of attraction among them and thus, cannot be considered negligible. Also, in this correction, the parameter ‘a’ is a variable which depends upon the nature of the gases.
(ii) Volume correction: According to this correction, the actual volume that an ideal gas takes up inside a container is equal to the parameter ‘nb’ as there are ‘n’ numbers of gaseous molecules inside the container. Thus, the volume of the gas is equal to the difference of the molar volume of the gas and the volume correction. Here, ‘b’ is the volume occupied by a single molecule of gas.
Hence, the correct option is B. intermolecular attractive forces and molecular volumes.

Note:
Van der Waals corrections are a prime example of the deviation of the real gases from their ideal behavior. The parameters ‘a’ and ‘b’ are different for different gases. These parameters link the real gases to their ideal behavior.