Question

Based on your measured potential for this cell and the literature value for the standard reduction potential for the ag/agcl reference electrode, what would you expect the overall potential to be for the spontaneous reaction between your cu2+/cu electrode and a standard hydrogen eletrode? type your calculation for the expected standard reduction potential vs the she as well as the % error between this value and the literature value.

Answer 1

The expected standard reduction potential for the Cu2+/Cu electrode versus the SHE would be -0.34 V based on the measured potential. To determine the percent error from literature values, you would use the experimental and literature values in the percent error formula. Positive Ecell values indicate spontaneous reactions while negative values suggest non-spontaneity.

Step-by-step explanation:

To calculate the expected standard reduction potential of the Cu2+/Cu electrode versus the Standard Hydrogen Electrode (SHE), we must use the provided literature values. The Cu2+/Cu couple has a measured potential of -0.34 V. Since the potential of the SHE is defined as 0 V, the overall cell potential (Ecell) is simply the potential of the Cu2+/Cu couple, which in this case is -0.34 V for the reaction where Cu is reduced and H2 is oxidized. The spontaneous reaction would, in this scenario, have a negative standard cell potential, indicating that, under standard conditions, this particular reaction with the SHE would not be spontaneous.

To find the percent error between the measured and expected values, you would use the formula: Percent Error = |(Experimental Value - Literature Value) / Literature Value| × 100%. If the expected standard reduction potential for a Cu2+/Cu electrode based on literature values was different from your measured -0.34 V, you would insert those values into the formula to calculate the percent error.

Remember that in electrochemistry, when using standard electrode potentials, a positive Ecell indicates a spontaneous reaction whereas a negative Ecell indicates a non-spontaneous reaction under standard conditions. All tabulated values of standard electrode potentials are listed for reactions written as reductions, which helps in comparing different substances.

Answer 2

I have attached an image that shows the measured cell potentials, and this question specifically refers to cell #4 with the following reaction:

Cu²⁺(aq) + 2Ag(s) → Cu(s) + 2Ag⁺(aq) Ecell = 0.137 V

We can separate this reaction into its two half reactions to identify the anode and cathode:

Cathode: Cu²⁺ + 2e⁻ → Cu E° = 0.34 V
Anode: Ag → Ag⁺ + 1e⁻ E° = 0.22 V

The formula for cell potential is:

Ecell = Ecathode - Eanode

We are asked to solve for the cell potential of the Cu²⁺/Cu electrode using the standard Ag/AgCl electrode potential and the measured potential:

0.137 V = Ecathode - 0.22 V
Ecathode = 0.137 + 0.22
Ecathode = 0.357 V

Now we can compare this value for the Cu²⁺/Cu electrode with the standard hydrogen electrode:

Ecell = 0.357 V - 0 V
Ecell = 0.357 V

We found a value of 0.357 V, however, the literature value is 0.34 V and now we can solve for the % error in our experimental value:

% error = ([experimental - theoretical]/[theoretical]) x 100%

% error = ((0.357 - 0.34)/0.34) x 100%

% error = 5 %

The experimental electrode potential for the Cu²⁺/Cu electrode was 0.357 V which has a 5% error compared to the literature value.