(a) Give the electrolyte of a named secondary electrochemical cell. (b) Consider the cell represented as shown below: \(Cu_{(s)}Cu^{2+}_{(aq)}/Zn^{2+}_{(aq)...
Question 1 Report
(a) Give the electrolyte of a named secondary electrochemical cell.
(b) Consider the cell represented as shown below: \(Cu_{(s)}Cu^{2+}_{(aq)}/Zn^{2+}_{(aq)}/Zn{(s)}\)
(i) What does the vertical double stroke represent?
(ii) Which of the metals forms the cathode?
(iii) Name the electrode to which each half-cell should be coupled if the oxidation potential of the half-cells are to be determined.
Answer Details
(a) Electrolyte of a named secondary cell
In the lead-acid accumulator, the electrolyte is dilute tetraoxosulphate(VI) acid (dilute sulphuric acid, H2SO4). (In the nickel-cadmium cell the electrolyte is potassium hydroxide solution.)
(b) The cell
\[Cu_{(s)} | Cu^{2+}_{(aq)} \parallel Zn^{2+}_{(aq)} | Zn_{(s)}\]
- (i) The vertical double stroke represents the salt bridge (the boundary between the two half-cells).
- (ii) Copper forms the cathode, because it is the less reactive metal, so reduction (gain of electrons) occurs at the copper electrode.
- (iii) To determine the oxidation (electrode) potential of each half-cell, each is coupled to the standard hydrogen electrode (SHE), which is taken as the reference with a potential of zero.
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