chemistry
posted by Hannah .
From the indicated voltages for the voltaic cell pictured, determine the standard electrode potential, E°M3+/M, if the metal, M, is each of the following.
description on the image:
in the left beaker there is one Cr3+ and one Cr2+ on the right beaker there is 'M'3+
the left one is oxidation the right is reduction.
heres the given:
La, E°cell = 1.96 V
so i have to find the Voltage of La i got 1.54 but it was wrong. don't you just use the equation
1.96 V= .424V(oxidation potential for the Cr2+... equation) + x
and solve for x??

What is La? Lanthanum. One of the various metals to plug into the problem? Do you want La^3+ + e ==> La^2+ or some other?
Anyway,
Yes, I think you do that for the equation I think you misplaced a sign.
Ecell = Eoxdn + Eredn
=1.96 = 0.424 + X
X = 1.96.424 = 2 something.