Question

Which of the following indicates a reaction with a positive ΔG? A. endergonic, spontaneous B. endergonic, not spontaneous C. exergonic, spontaneous D. exergonic, not spontaneous

Answer 1

Answer: B. endergonic, not spontaneous

Explanation:

Endergonic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and  $\Delta H$ for the reaction comes out to be positive.

The Gibbs equation is:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$= Gibb's free energy change

$\Delta H$ = enthalpy change

T = temperature

$\Delta S$ = entropy change

A reaction is non spontaneous when $\Delta G$= Gibb's free energy change is positive

$+ve=\Delta H-T(-ve)$

$+ve=\Delta H+ve$

$\Delta H=+ve$

Thus the reaction has to be endergonic.