KCET2020ChemistrySurface Chemistry
During adsorption of a gas on a solid at low temperature
Options
- AG < 0, H < 0, S < 0
- BG>0, H>0, S>0
- CG 0
- DG 0, S < 0
Correct answer
A. G < 0, H < 0, S < 0
Step-by-step solution
Adsorption is an exothermic process with H= negative and since, gas is being adsorbed to a solid the randomness of the gas is decreasing making S < 0 . Also, G= H-T S Here, T S is small negative value at low temperature and hence, G < 0 . Which supports the spontaneity of the adsorption.