Electrolysis
Answers are for parents and teachers.
1
Write the cathode and anode processes and overall equation for the electrolysis of AgNO₃ solution with inert electrodes.
Cathode: Ag⁺ + e⁻ → Ag; anode: 2H₂O – 4e⁻ → O₂ + 4H⁺; 4AgNO₃ + 2H₂O → 4Ag + O₂ + 4HNO₃.
2
How many moles of O₂ form when 72 g of water is electrolysed? (2H₂O → 2H₂ + O₂; M(H₂O) = 18)
2
3
In copper refining, what are the anode and cathode made of?
The anode is impure copper (it dissolves) and the cathode is pure copper on which pure copper is deposited.
4
Why is Na obtained from molten NaCl but not from NaCl solution?
In solution water is reduced more easily than Na⁺ at the cathode and H₂ is released; in a water-free melt only Na⁺ can be reduced.
5
How many grams of zinc are deposited from a Zn²⁺ solution when 20 A flows for 4825 s? (M(Zn) = 65, n = 2, F = 96500)
32.5 g