If ∆G° for a reaction is 1.93×10^6. Calculate the equilibrium constant if coditions are standard.

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Solution

The given question requires a basic understanding of thermodynamics and chemical kinetics

Gibbs free energy is actually a measure of the spontaneous behavior of a reaction.The reaction is spontaneous if the value of Gibbs free energy is negative .

Change In G=Change in H-T(change in S)

G=Gibbs free energy
H=Enthalpy
T=Temperature
S=Entropy

Gibbs free energy and the equilibrium constant can be related by the following equation

G=-RTlnk

G=Gibbs free energy
R=Universal Gas constant
T=Absolute temperature
Using standard conditions, we get

1.9310^6=-(8.314 Jmol^-1K^-1)(273K)(lnk)

1.9310^6=-(2269.7 Jmol^-1)lnk

1.9310^6=-(2269.7Jmol^-1)2.303 logk

Clearly
logk=-369.228

k=10^(-369.228)

Since the value of Gibbs energy is positive,the reaction can be considered as non spontaneous

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