A certain reaction has a ΔH of 12 kJ and a ΔS of 40 J K-1. The temperature above which the reaction becomes spontaneous is

Question

A certain reaction has a ΔH of 12 kJ and a ΔS of 40 J K-1. The temperature above which the reaction becomes spontaneous is (A) 27°C (B) 27 K (C) 300°C (D) 30°C

Tardigrade Admin · Accepted Answer

A reaction will be spontaneous , if Δ H-T Δ S=- ve or Δ H-T Δ S< 0 or T< (Δ H/Δ S) Now, (Δ H/Δ S)=(12 × 103/40)=300 K =300-273=27° C ∴ Above 27° C, the reactiá»n becomes spontaneous.

Q. A certain reaction has a $Δ H$ of $12 k J$ and a $Δ S$ of $40 J K^{- 1}$ . The temperature above which the reaction becomes spontaneous is

$2 7^{°} C$

$27 K$

$30 0^{°} C$

$3 0^{°} C$

$30 K$

A reaction will be spontaneous , if

$Δ H - T Δ S = - v e$ or $Δ H - T Δ S < 0$

or $T < \frac{Δ H}{Δ S}$

Now, $\frac{Δ H}{Δ S} = \frac{12 \times 1 0 ^{3}}{40} = 300 K$

$= 300 - 273 = 2 7^{\circ} C$

$∴$ Above $2 7^{\circ} C$ , the reactiọn becomes spontaneous.

Q. A certain reaction has a ΔH of 12kJ and a ΔS of 40JK−1. The temperature above which the reaction becomes spontaneous is

27°C

27K

300°C

30°C

30K

A reaction will be spontaneous , if ΔH−TΔS=−ve or ΔH−TΔS<0 or T<ΔSΔH​ Now, ΔSΔH​=4012×103​=300K =300−273=27∘C ∴ Above 27∘C, the reactiọn becomes spontaneous.