Question

Which one of the following is correct for the adsorption of a gas at a given temperature on a solid surface?

Options

• ΔH < 0, ΔS > 0

• ΔH > 0, ΔS < 0

• ΔH < 0, ΔS < 0

• ΔH > 0, ΔS > 0

Answer 1

ΔH < 0, ΔS < 0

Explanation:

For adsorption process, ΔH < 0 and ΔS < 0. 

The enthalpy (ΔH < 0) and randomness (ΔS < 0) of the gas molecules both drop as a result of the bond that the gas molecules make with the metal surface during the adsorption process.