The values of Δ H and Δ S for the reaction, C_ (graphite) +CO_2( g) 2 CO(g) are 170 kJ and 170 JK^ -1 , respectively. This reaction will be spontaneous at

Correct answer: C. 1110 ~K Key Idea For spontaneous process, Δ G 1000 & T=1110 ~K & aligned

NEET 2009

NEET 2009 · Chemistry · Thermodynamics (C)

The values of Δ H and Δ S for the reaction, C_ (graphite) +CO_2( g)...

The values of

\Delta H

and

\Delta S

for the reaction,

\mathrm{C}_{\text{(graphite) }}+\mathrm{CO}_2(\mathrm{ g}) \longrightarrow 2 \mathrm{CO}(\mathrm{g})

are

170 \mathrm{ kJ} and

170

\mathrm{JK}^{-1}

, respectively. This reaction will be spontaneous at

C. $1110 \mathrm{~K}$

Key Idea For spontaneous process,

\Delta \mathrm{G} < 0

\begin{aligned} & \Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S} \\ & \text{ Given, } \Delta \mathrm{H}=170 \mathrm{~kJ}=170 \times 10^3 \mathrm{~J} \\ & \Delta \mathrm{S}=170 \mathrm{JK}^{-1} \\ & \mathrm{~T}=\text{ ? } \\ & \Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S} \\ & 0 < 170 \times 10^3-\mathrm{T} \times 170 \\ & \mathrm{~T}>1000 \\ & \therefore \quad \mathrm{T}=1110 \mathrm{~K} \\ & \end{aligned}