Question

One of the assumptions of the kinetic molecular theory is that there are no intermolecular forces (attractive or repulsive) between gas particles (atoms or molecules). How would the presence of intermolecular forces affect the ideal gas equation (PV = nRT)? Again, in your response, please use terms that a high school senior who hasn’t taken AP chemistry might use.

Answer 1

When intermolecular forces of attraction are there , it means molecule come very close to each other. so when molecule come close to each there then bomabardment of molecules increase among each other .This creates more pressure. So we can say that pressure increases when molecules come close to each other. As molecule come close to each other ,means space occupied by molecules decreases as now they come close to each other as compared when they are far away from each other because no electrostatic repulsion was there. So we can say VOLUME decrease due to intermolecular forces of attraction.

If we combined the above two effects of intermolecular forces, we can write a equation in which Pressure is greater than Ideal gas pressure (used in PV=nRT) and Volume is less than volume used in ideal gas equation. This pressure and volume are changed by certain terms including 2 constants a and b (as shown in the image atttached).

a= representing intermolecular forces correction

b= volume occupied by single molecule.

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