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SingaporeChemistryQuick questions
Electrolysis
Quick questions on Electrolysis of aqueous solutions explained: O-Level Chemistry
7short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is discharge at the cathode (reactivity rule)?Show answer
At the cathode, the choice is between the metal ion and the hydrogen ion from water. The rule depends on reactivity:
What are writing the half-equations?Show answer
The electrode reactions are written as half-equations showing electrons:
What is effect on the solution?Show answer
Removing ions changes the solution. For copper(II) sulfate with inert electrodes, the blue colour fades as copper(II) ions are removed, and the solution becomes acidic as hydroxide is discharged at the anode leaving hydrogen ions and sulfate behind.
What are unbalanced half-equations?Show answer
Balance atoms and electrons; the oxygen half-equation needs four hydroxide ions and four electrons.
What is q1?Show answer
State the product at the cathode when aqueous sodium sulfate is electrolysed, and explain why. [2 marks]
What is q2?Show answer
State the product at the anode when concentrated sodium chloride solution is electrolysed. [1 mark]
What is q3?Show answer
Write the half-equation for the production of oxygen at the anode. [1 mark]
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