Question

The Nernst equation at 20oC is:

Eion= 58 millvolts/z. [log10 (ion)out/(ion)in]

Calculate the equilibrium potential for Cl- if the concentration of Cl- outside of the cell is 100 and the concentration inside of the cell is 10 mmol/liter.

a. 58 millivolts
b. +58 millivolts
c. -116 millivolts
d. 0

Answer 1

a. -58 millivolts

Step-by-step explanation:

The given Nernst equation is:

`E_(ion) = 58 millivolts /z \Big[ log_(10) \Big( ([ion]_(out))/([ion]_(in))\Big) \Big]}`

The equilibrium potential given by the Nernst equation can be determined by using the formula:

`E_(Cl^-) = (2.303*R*T)/(ZF) * log \frac{[Cl^-]_(out)} {[Cl^-]_(in)}`

where:

gas constant(R) = 8.314 J/K/mol

Temperature (T) = (20+273)K

= 298K

Faraday constant F = 96485 C/mol

Number of electron on Cl = -1

`E_(Cl^-) = \frac{2.303*8.314*298} {(-1)*(96845)} * log \frac{100} {10}`

`E_(Cl^-) = - 0.05814 \ volts`

`\mathsf{E_(Cl^-) = - 0.05814 * 1000 \ milli volts}`

`\mathsf{E_(Cl^-) \simeq - 58\ milli volts}`