Question

In the first step of glycolysis, the given two reactions are coupled. reaction 1:reaction 2:glucose+Pi⟶glucose-6-phosphate+H2OATP+H2O⟶ADP+PiΔG=+13.8 kJ/molΔG=−30.5 kJ/mol Answer the four questions about the first step of glycolysis. Is reaction 1 spontaneous or nonspontaneous?

Answer 1

Answer: Reaction 1 is non spontaneous.

Explanation:

According to Gibb's equation:

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

$\Delta G$ = Gibbs free energy  

$\Delta H$ = enthalpy change

$\Delta S$ = entropy change  

T = temperature in Kelvin

When $\Delta G$ = +ve, reaction is non spontaneous

$\Delta G$= -ve, reaction is spontaneous

$\Delta G$= 0, reaction is in equilibrium

For the given reaction 1: $glucose+Pi\rightarrow glucose-6-phosphate+H_2O$ $\Delta G=+13.8kJ/mol$

As for the reaction 1 , the value of Gibbs free energy is positive and thus the reaction 1 is non spontaneous.