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.
To determine the standard electrode potential, E°M3+/M, for the metal M, you need to use the given information about the voltaic cell and the equation you mentioned as well. However, it seems that you made a mistake in your calculation.
Let's break down the steps to find the standard electrode potential, E°M3+/M:
1. Identify the half-reactions: In the voltaic cell, oxidation occurs on the left side (Cr2+ → Cr3+) and reduction occurs on the right side (M3+ → M).
2. Write the half-reactions and their corresponding standard electrode potentials:
Oxidation half-reaction: Cr2+ → Cr3+ and its standard electrode potential is given as -0.424 V (note the sign should be negative).
Reduction half-reaction: M3+ → M, for which the standard electrode potential is unknown (E°M3+/M = x V).
3. Write the overall cell reaction: By combining the half-reactions, we get:
Cr2+ + M3+ → Cr3+ + M
4. Write the Nernst equation: The equation you mentioned can be used to calculate the cell potential (Ecell), but to determine the standard electrode potential (E°M3+/M) specifically, we use the Nernst equation:
Ecell = E°cell - (0.0592 V/n) * log(Q)
Here, Ecell is the cell potential (given as -1.96 V), n is the number of electrons transferred in the balanced cell reaction, and Q is the reaction quotient.
5. Determine n and Q: In the balanced cell reaction, one electron is transferred for each Cr2+ ion. Thus, n = 1. The reaction quotient, Q, for the given cell is not explicitly stated, but assuming the concentrations are standard (1 M), Q would be equal to 1.
6. Rearrange the Nernst equation: Using the values we have, the Nernst equation can be rearranged to solve for E°M3+/M:
E°cell = E°M3+/M + 0.0592 V * log(1)
-1.96 V = x V + 0.0592 V * 0
-1.96 V = x V
Therefore, the standard electrode potential, E°M3+/M, for metal M is -1.96 V.
In summary, you miscalculated the standard electrode potential for the given cell. By properly applying the Nernst equation, we find that the standard electrode potential, E°M3+/M, is -1.96 V.