4.1 Key findings & Analysis of results
(For our experiment, the metal with the higher reactivity series is placed at the anode, the metal that releases electrons).
From our data, our key findings are that the combination of copper +zinc produces the most voltage out of the three pairs, followed by copper+aluminium, and lastly zinc and aluminium. Anomalies include the fact that the combination of copper+zinc produced double the voltage compared to copper+aluminium.
4.2 Explanation of key findings
Working to explain key findings:
Copper gains 2e-
Aluminium donates 3e-
Zinc donates 2e-
Copper+Zinc:
Anode\; (oxidation): Zn(s) → Zn2+(aq) + 2e-
Cathode\;(reduction): Cu2+(aq) + 2e- → Cu(s)
-----------------------------------------------------------------------
Net Equation: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
Copper+Aluminium:
Anode\; (oxidation): 2[Al(s) → Al3+ +3e-]
Cathode\; (reduction) : 3[Cu2+ + 2e- → Cu(s)]
-----------------------------------------------------------------------
Net Equation: 3(Cu2+) + 2(Al3+) → Al3+ + Cu(s)
Zinc+Aluminium:
Anode\; (oxidation): 2[Al(s) → Al3+ + 3e-]
Cathode\; (reduction) : 3[Zn2+ + 2e- → Zn(s)]
-----------------------------------------------------------------------
Net Equation: 2[Al(s)] + 3[Zn2+] → 2[Al3+] + 3[Zn(s)]
Our explanation for the anomalie between Copper + Zinc and Copper + Aluminium, is the fact that there is highly a random error that cannot be traced and eliminated, which caused the statistical anomaly of the voltage produced being doubled of what should be less.
The random anomalie happens as some of the electrons lost from aluminium (Specifically 3e-) went into the solution, as the metal is in contact with the solution. Since a limitation of our research is keeping the purity of the metal, there might be instances where the impurities in the solution will cause the electrons of the metal will travel into the solution, which causes a reduction of voltage in the wires to be detected by the voltmeter.
4.3 Evaluation of Hypothesis
Our hypothesis was correct, as the metals with the highest difference in reactivity produced the most electricity during redox-reaction, as the electrons produced by the anode will be able to be gained more by the cathode due to their reactivity difference, thus producing more electricity when more electrons travel.
Figure 4: Metal Reactivity Series Figure 5: Standard Reduction Potential
4.4 Limitations and Areas for improvement
Some of our limitations are that there may be results that are not as accurate compared to being perfect as when the metals were placed into the solution, the reaction may have started before the data was manually measured. Another limitation of our experiment is our resources and materials provided by the school, and our ability and equipment to maintain the purity of the metals and solutions.