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Electrolysis

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Question 16

An apparatus is used to demonstrate the electrolysis of molten lead(II) bromide.

A student records these observations:

  • beads of a shiny grey liquid form at one of the electrodes
  • reddish-brown fumes form at the other electrode
  • the lamp in the circuit goes out after the heating is stopped and the lead(II) bromide cools
a.

State what is meant by the term electrolysis.

[2]
b.

State why graphite is more suitable to use for the electrodes than zinc in this electrolysis.

[2]
c.

Which of these is a correct statement for this electrolysis?

  • A the reddish-brown substance is bromide
  • B both products are compounds
  • C the shiny grey liquid forms at the negative electrode
  • D the reddish-brown substance forms at the negative electrode
[1]
d.

The student writes this ionic half-equation for the reaction that forms the reddish-brown substance:

2Br−+2e−→2Br 2\text{Br}^- + 2\text{e}^- \rightarrow 2\text{Br} 2Br−+2e−→2Br

Identify the two mistakes in this ionic half-equation.

[2]
e.

The lamp goes out after the heating is stopped and the lead(II) bromide solidifies because current is no longer flowing. Explain why current can no longer flow.

[2]

Electrolysis Questions

  1. IGCSE
  2. /Chemistry
  3. /Electrolysis