The values of ΔH and ΔS of a certain reaction are - 400 kJ mol-1 and -20 kJ mol-1K-1 respectively. The temperature below which the reaction is spontaneous is

Question

The values of ΔH and ΔS of a certain reaction are - 400 kJ mol-1 and -20 kJ mol-1K-1 respectively. The temperature below which the reaction is spontaneous is (A) 100 K (B) 20°C (C) 20 K (D) 120°C

Tardigrade Admin · Accepted Answer

Given, Δ H =-400 kJ mol -1 Δ S =-20 kJ mol -1 K -1 Gibbs Helmholtz equation is Δ G=Δ H-T Δ S For a reaction to be spontaneous, Δ G must be less than 0 , i.e., negative. ∴ 0 ≥ Δ H-T Δ S T Δ S ≤ Δ H T ≤ (Δ H/Δ S) ≤ (-400/-20) ≤ 20 K

Q. The values of $Δ H$ and $Δ S$ of a certain reaction are $- 400 k J m o l^{- 1}$ and $- 20 k J m o l^{- 1} K^{- 1}$ respectively. The temperature below which the reaction is spontaneous is

$100 K$

$2 0^{\circ} C$

$20 K$

$12 0^{\circ} C$

Q. The values of ΔH and ΔS of a certain reaction are −400kJmol−1 and −20kJmol−1K−1 respectively. The temperature below which the reaction is spontaneous is

100K

20∘C

20K

120∘C

Given, ΔH=−400kJmol−1 ΔS=−20kJmol−1K−1 Gibbs Helmholtz equation is ΔG=ΔH−TΔS For a reaction to be spontaneous, ΔG must be less than 0 , i.e., negative. ∴0≥ΔH−TΔS TΔS≤ΔH T≤ΔSΔH​≤−20−400​≤20K

Q. The values of $Δ H$ and $Δ S$ of a certain reaction are $- 400 k J m o l^{- 1}$ and $- 20 k J m o l^{- 1} K^{- 1}$ respectively. The temperature below which the reaction is spontaneous is

$100 K$

$2 0^{\circ} C$

$20 K$

$12 0^{\circ} C$