If for a certain reaction Δ r H is 30 kJmol - 1 at 450 K , the value of Δ r S (in JK - 1 mol - 1 ) for which…

If for a certain reaction ΔrH is 30 kJmol-1 at 450K, the value of ΔrS (in JK-1mol-1) for which the same reaction will be spontaneous at the same temperature is (Nearest Integer)
  1. 70
  2. -33
  3. 33
  4. -70

Solution

ΔG=ΔH-TΔS
For spontaneous,

ΔG<0
ΔH-TΔS<O
ΔS>ΔHT
ΔS>30×103Jmol-1450K
ΔS>66.6 Jmol-1K-1 (Check by options)

So, option (1) , i.e. \(70 \mathrm{~J} \mathrm{mol}^{-1} \mathrm{~K}^{-1}\) satisfies it.

Asked in: NEET 2020 (Phase 2)

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