Question

A gas described by Van der Waals equation _____.

• A. behaves similar to an ideal gas in the limit of large molar volumes.
• B. behaves similar to an ideal gas in the limit of large pressures.
• C. is characterized by van der Waals coefficients that are dependent on the identity of the gas but are independent of the temperature.
• D. has the pressure that is lower than the pressure exerted by the same gas behaving ideally.

Answer 1

The correct option is D

has the pressure that is lower than the pressure exerted by the same gas behaving ideally.

Van der Waals equation is

$(p+\frac{n^{2}a}{V^2})(V-nb)=nRT$

At low pressure, when the sample occupies a large volume, then the intermolecular forces do not play any significant role and the gas behaves virtually perfectly ideal

Constants a and b are called Van der Waals constants and their value depends on the characterstic of a gas. Value of "a" is a measure of magnitude of intermolecular attractive forces within the gas and is independent of temperature and pressure.

The observed P correction term is added as

$P_{ideal}=P_{real}+\frac{a{n}^2}{V^2}$

Pressure exerted by real gas is lower than the pressure exerted by the ideal gas.