### Gibbs Free Energy

Posted:

**Mon Feb 25, 2019 12:43 am**Reaction 1: Fructose-6-phosphate +ATP --> Fructose-1,6-biphosphate + ADP deltaG = -13.7 kJ/mol

Reaction 2: Fructose-6-phosphate + HPO4 2- --> Fructose-1,6-biphosphate +H20 deltaG = 16.5 kJ/mol

To find the standard Gibb's free energy for ATP hydrolysis, my TA multiplied the Gibbs free energy of the first reaction by 1 and the Gibbs free energy by -1. Then to find the standard Gibb's free energy, he added the two and got -30.2 kJ/mol.

I don't really understand why you have to multiply by 1 and -1. Why do you need to multiply one by 1 and the other by -1?

Reaction 2: Fructose-6-phosphate + HPO4 2- --> Fructose-1,6-biphosphate +H20 deltaG = 16.5 kJ/mol

To find the standard Gibb's free energy for ATP hydrolysis, my TA multiplied the Gibbs free energy of the first reaction by 1 and the Gibbs free energy by -1. Then to find the standard Gibb's free energy, he added the two and got -30.2 kJ/mol.

I don't really understand why you have to multiply by 1 and -1. Why do you need to multiply one by 1 and the other by -1?