Use the voltaic cell and information below to answerthe following questions. Alu

Question

Use the voltaic cell and information below to answerthe following questions.

Aluminum is a light silver metal and Al+3 is a colorless ion in solution. Cobalt is a dark grey metal while Co+2 is a light blue ion in solution.

1. Write the balanced redox reaction that the cell represents (include phases).

2. Determine the Ecell (include units).

?3. Describe the observations/changes that would happen in the cell (in terms of the electrodes, solutions, concentrations, etc.) as the redox reaction occurs

Explanation / Answer

Answer – We are given, cell with 1.0 M Ag(NO3)3 and 1.0 M Co(NO3)2. There are also given standard cell potential of each half reaction of each metal.

We know the high reduction potential value is giving the reduction and lower on is for oxidation, so Co gets reduced and Al get oxidized.

1) The balanced redox reaction for the given cell is as follow –

The half reactions –

Al (s) -----> Al3+ (aq) + 3e-

Co2+(aq) + 2 e- -----> Co(s)

Now we need to balance the electrons

2 Al (s) -----> 2 Al3+ (aq) + 6e-

3 Co2+(aq) + 6 e- -----> 3 Co(s)

Redox reaction - 2 Al (s) +3 Co2+(aq) ----->2 Al3+ (aq) +3 Co(s)

2) First we need to calculate the standard cell potential

2 Al (s) -----> 2 Al3+ (aq) + 6e- , Eo = 1.66 V

3 Co2+(aq) + 6 e- -----> 3 Co(s) , Eo = -0.28 V

2 Al (s) +3 Co2+(aq) ----->2 Al3+ (aq) +3 Co(s), Eocell = 1.38 V

We know the Nernst equation –

Ecell = Eocell – 0.0591/n * log Q

        = 1.38 V – 0.0591 / 6 * log (1.0)2 / (1.0)3

       = 1.38 V

3) In this cell there is Co(s) acts as cathode and Al act as anode. As reaction proceed there is Al gets dissolve in the solution 1.0 M Ag(NO3)3 and Co gets deposited. The concentration of Al3+ increased and the concentration of Co2+ gets decreased. In the Al3+ solution there is no change in color and Co2+ is change light blue to dark gray.

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