For independent process at 300 K. | Process | $\Delta \mathbf{H} / \mathbf{kJ ~ mol}^{-\mathbf{1}}$ | $\Delta \mathbf{S} / \mathbf{J ~ K}^{-\mathbf{1}}$ | |---------|-------|-------| | A | -25 | -80 | | B | -22 | 40 | | C | 25 | -50 | | D | 22 | 20 | The number of non-spontaneous process from the following is ______.

JEE Main · 2023 · 24 Jan 2023 · Shift 1 · Chemical Thermodynamics

For independent process at 300 K.

The number of non-spontaneous process from the following is ______.

Answer: 2

A process is spontaneous when

Δ G = Δ H - T Δ S

is negative; here

T = 300 K

and the entropies are in

J K^{- 1}

. For A,

Δ G = - 25000 - 300 (- 80) = - 1000 J mo l^{- 1}

, and for B,

Δ G = - 22000 - 300 (40) = - 34000 J mo l^{- 1}

; both are negative and spontaneous. For C,

Δ G = 25000 - 300 (- 50) = + 40000 J mo l^{- 1}

, and for D,

Δ G = 22000 - 300 (20) = + 16000 J mo l^{- 1}

; both are positive and non-spontaneous. The number of non-spontaneous processes is two.

JEE Main · 2023 · 24 Jan 2023 · Shift 1 · Integer answer