The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by $\Delta_{\mathrm{r}} \mathrm{G}^{0}=\mathrm{A}-\mathrm{BT}$ Where $A$ and $B$ are non - zero constant. Which of the following is TRUE about this reaction?

(A) Endothermic if $\mathrm{A}>0$

(B) Exothermic if $\mathrm{A}>0$ and $\mathrm{B}<0$

(C) Endothermic if $\mathrm{A} 0$

(D) Exothermic if $\mathrm{B}<0$

JEE Main · 2019 · 11 Jan 2019 · Shift 2 · Chemical Thermodynamics

The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by

Δ_{r} G^{0} = A - BT

Where

A

and

B

are non - zero constant. Which of the following is TRUE about this reaction?

Answer: (A)

Comparing the given

Δ_{r} G^{\circ} = A - B T

with the thermodynamic relation

Δ G^{\circ} = Δ H^{\circ} - T Δ S^{\circ}

identifies

A = Δ H^{\circ}

and

B = Δ S^{\circ}

. An endothermic reaction has

Δ H^{\circ} > 0

, which is exactly the condition

A > 0

JEE Main · 2019 · 11 Jan 2019 · Shift 2 · Single correct option