Experiment 3: Constructing a zinc/ iron cellExperiment 2: Constructing a zinc/ copper cell · A zinc/ copper cell was set up as it was shown in the figure in laboratory manual. · The zinc and copper were cleaned with emery paper before use. · 1.0 M zinc sulphate and copper sulphate solutions were used for the electrolytes and a strip of filter paper was soaked in saturated potassium nitrate for the salt bridge. · The polarity of the electrodes was predicted then the e.m.f of the cell was measured using a high resistance voltmeter. · The cell e.m.f was recorded. · Bearing in mind the relative tendencies of zinc, iron and copper to lose electrons, it was predicted whether the e.m.f of the zinc/iron cell would be less than or greater than that of zinc/ copper. Experiment 3: Constructing a zinc/ iron cell · A zinc/ iron cell was set up using a similar arrangement to the previous one with a Fe/Fe2+ half-cell instead of a copper one. · The copper half-cell was kept for a later experiment. · A clean iron nail was used for the electrode and an acidified 1.0 M iron (II) sulphate solution was used as the electrolyte. · A fresh salt bridge was used. · The polarity of the cell was predicted before measuring the e.m.f · The E0cell was recorded. · Assuming each half-cell in a cell makes a fixed, independent contribution to E0cell by using previous results, it was predicted the E0cell of an iron/ copper cell. · An equation for the cell reaction was wrote.
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