Question

The correction factor ‘a’ to the ideal gas equation corresponds to

• A. density of the gas molecules
• B. electric field present between the gas molecules
• C. volume of the gas molecules
• D. forces of attraction between the gas molecules

Answer 1

The Correct Option is D

The ideal gas equation is given by:

\( PV = nRT \)

where \( P \) is the pressure, \( V \) is the volume, \( n \) is the number of moles, \( R \) is the universal gas constant, and \( T \) is the temperature.

However, real gases deviate from ideal behavior at high pressure and low temperature because of interactions between gas molecules. To account for these deviations, van der Waals introduced corrections to the ideal gas law, resulting in the van der Waals equation:

\( \left( P + \frac{a n^2}{V^2} \right)(V - n b) = nRT \)

In this equation:

• \( a \) is the van der Waals constant associated with the intermolecular forces of attraction between gas molecules. It corrects the pressure term.
• \( b \) is the van der Waals constant associated with the volume occupied by gas molecules. It corrects the volume term.

The correct answer to the question is: forces of attraction between the gas molecules. The constant \( a \) reflects the magnitude of the attractive forces between the molecules. If \( a \) is larger, it indicates stronger attractive forces among molecules, which reduces the pressure exerted by the gas.

Let's rule out other options:

1. Density of the gas molecules: This is not directly related to the correction \( a \), as density pertains to the number of molecules per unit volume, not the interactions between individual molecules.
2. Electric field present between the gas molecules: The correction \( a \) does not represent any electric fields, but rather the general attractive forces (such as van der Waals forces).
3. Volume of the gas molecules: The correction for the volume of the molecules is given by \( b \), not \( a \).

Thus, the correct understanding is that the correction factor \( a \) corresponds to the forces of attraction between the gas molecules.