Chemistry · The second law of thermodynamics: Spontaneity of processes, Delta S of the universe and Delta G of the system as criteria for spontaneity

During adsorption, enthalpy and entropy of the system are but must be

During adsorption, enthalpy and entropy of the system are but \( \Delta G \) must be

  • A. negative, positive
  • B. negative, negative
  • C. positive, negative
  • D. positive, positive

Step-by-step solution

Adsorption is an exothermic process, so enthalpy change (ΔH) is negative. The randomness of molecules decreases as they are adsorbed onto a surface, leading to a decrease in entropy (ΔS negative). For a spontaneous process, ΔG must be negative, which is achieved at low temperatures as ΔG = ΔH - TΔS (with ΔS negative, -TΔS positive, but overall negative).
Practise more in this unitView MCQsSign up for full question bank