For independent processes at 300 K | Process | Δ H/kJ mol^-1 | Δ S/J K^-1 | |---------|------------------------|----------------------| | A | -25 | -80 | | B | -22 | 40 | | C | 25 | -50 | | D | 22 | 20 | The number of non-spontaneous processes from the following is ______

For independent processes at 300 K | Process | Δ H/kJ… — JEE Main 2023 Chemistry PYQ

JEE Main 2023 · 24 Jan · Shift 1 · Paper-1(B.E./B. Tech.) · numerical answer

For independent processes at 300 K

Process	$\Delta H$ /kJ mol $^{-1}$	$\Delta S$ /J K $^{-1}$
A	$-25$	$-80$
B	$-22$	$40$
C	$25$	$-50$
D	$22$	$20$

The number of non-spontaneous processes from the following is ______

Show answer and solution

Answer: 2

Solution

Calculate ΔG = ΔH - TΔS at T = 300 K for each process (spontaneous if ΔG < 0):

A: ΔG = -25000 - 300(-80) = -25000 + 24000 = -1000 J/mol < 0 → Spontaneous

B: ΔG = -22000 - 300(40) = -22000 - 12000 = -34000 J/mol < 0 → Spontaneous

C: ΔG = 25000 - 300(-50) = 25000 + 15000 = 40000 J/mol > 0 → Non-spontaneous

D: ΔG = 22000 - 300(20) = 22000 - 6000 = 16000 J/mol > 0 → Non-spontaneous

Processes C and D are non-spontaneous, giving the answer 2.

[JEE Main 2023 · 24 Jan · Shift 1 · Paper-1(B.E./B. Tech.)]

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