# physics

posted by
**Ann**
.

for the current density equation (I) , solve for dV/dx when I = 0

I = - [ uz2F[C] dV/dx + uzRT d[C]/dx]

According to your equation.

dV/dx= uzRT/uz2[C] d[C]/dx

I am uncertain what your symbols mean.

It's supposed to be the current density equation I think??

My teacher also gave the form:

I = -(ƒÊ(z^2)F(C))(dv/dt)+ (UZRT d(C)/dx))

C is concentration.

z valence

F Faraday constant

U I am not sure of

R is gas constant

T is temp

and he wanted us to set I to 0 and solve.

also, he wanted us to show how

RT/zF ln (C)out/(C)in ends up to be

58millivolts log10 (C)out/(C)in

with constants:

deg K = absolute T = deg C + 273.16

1 cal = 4.2 Joules

1V = 1Joule/Coulomb

F = Faradaysf Constant (96,480 Coulombs/mol)

R = Gas Constant (1.987 cal / mol degK)

e = elementary electrical charge = 1.602x10-19 C

Avogadrofs Number 6.02x1023 molecules/mole

I am really confused about the ln and log10 and how to get 58

dV/dx= uzRT/uz2[C] d[C]/dx

integrate with respect to x to get

v= uzRT/uz2 ln(C)

Î¼ is mobility of ions in solution in units of cm2v-1s-1