InterviewSolution
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InterviewSolution
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Predicating the products of electrolysis: What do you expect to be the half reactions in the electrolysis of aqueous `Na_(2)So_(4)` solution. Strategy: Before we look at the electrode reations, we should consider the following facts: (1) Since `Na_(2)So_(2)` does not hydrolyze in water, the `pH`of the solution is close to `7. (2)` The `Na^(+)` ions are not reduced at the cathode and the `SO_(4)^(2-)` ions are not oxidized at the anode. These conclusions are drawn from the electrolysis of water in the presence of sulphuric acid in aqueous sodium chloride solution. |
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Answer» The electrode reaction are Anode: `2H_(2)(l) rarr O_(2)(g) + 4H^(+)(aq.)+4e^(-)` Cathode: `2H_(2)O(l)+2e^(-) rarr H_(2)(g)+2OH^(-)` The overall reaction, obtained by doubling the cathode reaction coefficients and adding the result to the anode reaction, is `6H_(2)O(l) rarr 2H_(2)(g)+O_(2)(g)+4H^(+)(aq.)+4OH^(-)(aq.)` If the `H^(+)` and `OH^(-)` ions ar allowed to mix, then `4H^(+)(aq.)+4OH^(-)(aq.) rarr (4H_(2))(l)` and the overall reaction becomes `2H_(2)O(l) rarr 2H_(2)(g)+O_(2)(g)` |
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