Question

In the situations described below, what is the free energy change if 1 mole of Na+ is transported across a membrane from a region where the concentration is 267 μM to a region where it is 80 mM? (Assume T=37∘C.)

Answer 1

ΔG = 19.5 kJ/mol

Step-by-step explanation:

The free energy change for moving an ion is given by the following formula:

ΔG = RT㏑(C₂/C₁) + ΖЭψ

where R is molar gas constant = 8.315 J/mol;

T = 273 +37 = 310 K;

C₂ is concentration outside the cell = 267 μM = 0.000267 M;

C₁ is concentration inside the cell = 80 mM = 0.005 M;

Ζ is charge on ion = +1;

Э is Faraday's constant = 96500 J/V;

ψ is standard transmembrane potential = 0.05 V

ΔG = (8.315 J/mol * 310 K) ㏑(0.08/0.000267) + 1 *(96500 J/V * 0.05 V)

ΔG = (14692.60 + 4825)J/mol

ΔG = 19517.6 J/mol

ΔG = 19.5 kJ/mol