1. Δ G is negative but Δ H and Δ S are positive 2. Δ G , Δ H and Δ S all are negative 3. Δ G and Δ H are negative but Δ S is positive 4. Δ G and Δ S are negative but Δ H is positive

Answer: 2. Δ G , Δ H and Δ S all are negative Key idea: adsorption is spontaneous, exothermic and reduces the freedom of the adsorbate. Spontaneous: Δ G<0 . Particles stick to the surface and release heat: Δ H<0 . Gas or solute molecules become confined on the surface, so randomness drops: Δ S<0 . Since Δ G=Δ H-TΔ S , a negative Δ H outweighs the -TΔ S term, giving negative Δ G . So all three are negative: option 2.

Topic: Lyophilic and lyophobic sols· Principles Related to Practical Chemistry

Which one of the following characteristics is associated with adsorption ?

1. \(\Delta G\) is negative but \(\Delta H\) and \(\Delta S\) are positive

2. \(\Delta G\), \(\Delta H\) and \(\Delta S\) all are negative

3. \(\Delta G\) and \(\Delta H\) are negative but \(\Delta S\) is positive

4. \(\Delta G\) and \(\Delta S\) are negative but \(\Delta H\) is positive

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Answer: 2. \(\Delta G\), \(\Delta H\) and \(\Delta S\) all are negative

Key idea: adsorption is spontaneous, exothermic and reduces the freedom of the adsorbate.

Spontaneous: \(\Delta G<0\).
Particles stick to the surface and release heat: \(\Delta H<0\).
Gas or solute molecules become confined on the surface, so randomness drops: \(\Delta S<0\).

Since \(\Delta G=\Delta H-T\Delta S\), a negative \(\Delta H\) outweighs the \(-T\Delta S\) term, giving negative \(\Delta G\). So all three are negative: option 2.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Which one of the following characteristics is associated with adsorption ?

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