Chemistry
Acidulated water is electrolysed using platinum electrodes. Answer the following questions:
(a) Why is dilute sulphuric acid added to water?
(b) Write the reaction taking place at the cathode.
(c) What is the observation at the anode?
Answer
(a) Water in pure state consists almost entirely of molecules. It is a polar covalent compound and can form ions when traces of dilute sulphuric acid is added.
(b) 4H+ + 4e- ⟶ 4H
2H + 2H ⟶ 2H2
(c) At the anode (positive electrode) hydroxide ions are preferentially discharged, producing oxygen gas:
4OH- - 4e- ⟶ 4OH
4OH ⟶ 2H2O + O2
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