post lab
DESCRIPTION
Phychem Lab 2 postlabTRANSCRIPT
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