The electrolysis of molten compounds
2 marks · EasyMolten calcium iodide () is electrolysed using inert electrodes.
Write the half-equation for the reaction that occurs at the cathode during the electrolysis of molten calcium iodide.
Explain why iodide ions move to the anode in this process.
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)
(b) Because iodide ions are negatively charged and are attracted to the positive electrode (the anode).
Common mistakes: Swapping cathode/anode products; missing charge on ions; incorrect reasoning about charge
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Marking points
M1 (a) · 1 mark · Correct half-equation for reduction at cathode:
M2 (b) · 1 mark · Explains that iodide ions move to the anode because they are negative and attracted to the positive electrode.
Worked solution
a) The reaction at the cathode is:
At the cathode, calcium ions () gain two electrons to form calcium metal.
b) Iodide ions move to the anode because they are negatively charged and are attracted to the positive electrode.