A student hypothesised that polishing the zinc, Zn, electrode in an Fe–Zn galvanic cell would increase the current produced by the cell - VCE - SSCE Chemistry - Question 10 - 2021 - Paper 1

To test the hypothesis about the effect of polishing the Zn electrode on the current produced in an Fe–Zn galvanic cell, the most valid method would be to measure the change in mass per unit time of the Fe electrode in the same galvanic cell before and after polishing the Zn electrode. This method provides direct evidence of how the polishing affects the electrochemical reaction occurring in the cell, thereby influencing the current produced. By comparing the mass change associated with the anodic reaction (Zinc being oxidized) and the cathodic reaction (Iron being reduced), we can infer whether the polishing process increases the current output.

In contrast, researching literature or measuring conductivity does not provide direct experimental evidence. Similarly, comparing different cells could lead to confounding variables, as there may be differences in the cells that could skew results.