Question

on 10 of 11 What is the equilibrium membrane potential due to Nat ions if the extracellular concentration of Nat ions is 138 mM and the intracellular concentration of Na ions is 33 mM at 20 C? equilibrium membrane potential: mV

Answer 1

For concentration cell, cathode and anode are same electrode

So, Eo = 0

Number of electron being transferred in balanced reaction is 1

So, n = 1

If E is positive anode will be the one with lower concentration

use:

E = Eo - (2.303*RT/nF) log {[Na+] at anode/[Na+]at cathode}

Here:

2.303*R*T/F

= 2.303*8.314*298.0/96500

= 0.0591

So, above expression becomes:

E = Eo - (0.0591/n) log {[Na+] at anode/[Na+]at cathode}

E = 0 - (0.0591/1) log (0.033/0.138)

E = 3.674*10^-2 V

= 36.7 mV

Answer: 36.7 mV