Chemistry – Metals - Corrosion of metals | e-Consult

Control Variable: A crucial control variable is the amount of zinc coating applied to each piece of metal. The thickness of the zinc layer should be kept constant for both the iron and copper samples. This ensures that the only difference between the samples is the base metal being protected.

Independent Variable: The independent variable is the type of metal being protected. The student should have two groups: one group with iron coated in zinc and another group with copper coated in zinc. The presence or absence of iron in the base metal is what's being manipulated.

Analysis of Results: The student should calculate the percentage mass loss for each sample after a week. This is done by subtracting the mass of the sample after a week from the initial mass and dividing by the initial mass, then multiplying by 100. The formula is: Percentage Mass Loss = [(Initial Mass - Final Mass) / Initial Mass] x 100.

The student should then compare the percentage mass loss of the iron and copper samples. If the iron sample shows a significantly lower percentage mass loss than the copper sample, this would indicate that galvanising is effective in preventing corrosion of iron. The copper sample, being more resistant to corrosion than iron, would likely show a lower mass loss regardless of the zinc coating. The results should be presented in a table to clearly show the mass loss for each sample.