Question

For which δg°rxn = –30.5 kj/mol at 37.0 °c and ph 7.0. calculate the value of δgrxn in a biological cell in which [atp] = 5.0 mm, [adp] = 0.10 mm, and [hpo42–] = 5.0 mm.

Answer 1

We are given ΔG°rxn = -30.5 kJ/mol for the following reaction:

ATP + H₂O → ADP + HPO₄²⁻

We are given a series of concentrations for each of the species and are asked to find the value of ΔG for the reaction. We can use the following formula:

ΔGrxn = ΔG°rxn + RTlnQ

We can use R = 0.008314 kJ/molK; T = 335.15 K and Q is the reaction quotient which can be found as follows, and be sure to first convert each concentration of mM to M:

Q = [ADP][HPO₄²⁻]/[ATP]
Q= [0.00010][0.005]/[0.005]
Q = 0.0001

Now we can use the above formula to solve for ΔGrxn.

ΔGrxn = -30.5 kJ/mol + (0.008314)(310.15)ln(0.00010)
ΔGrxn = -54.3 kJ/mol

The value of ΔGrxn = -54.3 kJ/mol.