Post Lab

Dayao, Jeseca D.A.De Guzman, John Wilbert N.

ResultsAverage emf of the different electrodes

Electrodes Anode (-) Cathode (+) Average emf (v)

Zn/Zn2+ & Pb/Pb2+

Zn/Zn2+ Pb/Pb2+ 0.565

Zn/Zn2+ & Fe2+,Fe3+

Zn/Zn2+ Fe/Fe3+ 0.456

Pb/Pb2+ & Fe2+,Fe3+

Pb/Pb2+ Fe/Fe3+ 0.064

Cu/Cu2+ & Pb/Pb2+

Pb/Pb2+ Cu/Cu2+ 0.0585

Al/Al3+ & Pb/Pb2+

Al/Al3+ Pb/Pb2+ 0.1225

ResultsCell Diagrams

Electrodes Cell DiagramZn/Zn2+ & Pb/Pb2+ Zn| ZnSO4(aq)||Pb(NO3) 2(aq) |PbZn/Zn2+&Fe2+,Fe3+ Zn| ZnSO4(aq)||Fe3+ (aq)|FePb/ Pb2+&Fe2+,Fe3+ Pb|Pb(NO3) 2(aq)|| Fe3+ (aq)|FeCu/Cu2+ & Pb/Pb2+ Pb|Pb(NO3) 2(aq)||CuSO4(aq)|CuAl/Al3+ & Pb/Pb2+ Al|Al(NO3) 2(aq))||Pb(NO3) 2(aq)|Pb

ResultsOverall reaction and Theoretical emf

Electrodes Overall Reaction emf (theo) (V)Zn/Zn2+ & Pb/Pb2+

Zn+Pb2+ → Zn2+ +Pb 0.636

Zn/Zn2+&Fe2+,Fe3+

Zn+Fe3+ → Zn2++Fe 0.721

Pb/ Pb2+&Fe2+,Fe3+

Pb+Fe3+ → Pb2+ +Fe 0.079

Cu/Cu2+ & Pb/Pb2+

Pb+Cu2+ → Cu+Pb2+ 0.465

Al/Al3+ & Pb/Pb2+

Al+Pb2+ → Pb+ Al3+ 1.551

ResultsComparison of Experimental Data with Theoretical Data

Electrodes emf (theoretical)

emf (experimental)

% error

Zn/Zn2+ & Pb/Pb2+

0.636 0.565 11.16%

Zn/Zn2+&Fe2+,Fe3+

0.721 0.456 35.75%

Pb/ Pb2+&Fe2+,Fe3+

0.079 0.064 18.99%

Cu/Cu2+ & Pb/Pb2+

0.465 0.0585 87.42%

Al/Al3+ & Pb/Pb2+

1.551 0.1225 92.10%

ConclusionThe experiment was able to meet its objective

having come up with the values of the electromotive force of each galvanic cell. Although the experimental data had resulted to a significant deviation from the computed values due to process errors, the positive values of the experimental data implies that all the reaction are spontaneous.

Recommendationsthe materials involved should be cleaned

properlybest to use a digital multimeter highest emf reading that should be recorded salt bridge should be maintained wet with

KCl solution in weighing the solutes, getting the exact

weight is not a necessity

Questions1. What could have happened if the alligator

clips were also submerged into the solution when the half-cells were being prepared? How would this affect the result of the experiment and why?

2. What does a negative readfing in the multimeter indicate?

3. How would the result of the experiment be affected if the electrodes of the half-cells were interchanged instead of the multimeter terminal?

4. How is the significance of electron affinity and electron negativity of the electrodes on the mef of the galvanic cell? Explain briefly