Passing electricity through compounds: electrolysis
4 marks · NormalAn experiment is set up to investigate the electrolysis of molten potassium iodide using inert carbon electrodes.
State the name given to the liquid that conducts electricity during electrolysis.
Describe how you would safely set up an experiment to carry out electrolysis on molten potassium iodide, naming the electrodes you would use.
State one safety precaution you should take during this experiment.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) electrolyte
(b) Set up inert (carbon or platinum) electrodes in molten potassium iodide in a heat-resistant crucible, connect electrodes to power supply. · must show naming electrodes as carbon or platinum, mentioning molten potassium iodide, use of heat-resistant crucible/beaker, connection to power supply
(c) Wear eye protection or use heat-resistant gloves or use tongs
Common mistakes: not mentioning molten; giving wrong electrode material
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly names the liquid as 'electrolyte'
M1 (b) · 1 mark · Describes using inert electrodes (carbon or platinum) in molten potassium iodide
M1 (b) · 1 mark · Mentions correct setup: electrodes in molten compound with connection to a power supply OR use of suitable crucible
B1 (c) · 1 mark · States a valid safety precaution (e.g., wearing safety goggles, using heat protection)
Worked solution
a) Electrolyte
b) Place inert carbon (or platinum) electrodes into a heat-resistant crucible containing molten potassium iodide. Connect the electrodes to a power supply so current passes through the liquid.
c) Wear safety goggles when heating potassium iodide, as high temperatures are used.