IB Chemistry SL Reactivity 3.2.8 Electrolytic Cells

Practise explaining how an external power supply drives a non-spontaneous redox reaction in an electrolytic cell. For molten salts, identify the mobile ions, send cations to the…

Exam points

explain that mobile ions conduct current through a molten electrolyte between electrodes
send cations to the cathode for reduction and anions to the anode for oxidation
deduce molten-salt products and write balanced electrode half-equations from the ions present

[Maximum number: 4]

Draw a diagram of an electrolytic cell for the electrolysis of molten nickel(II) bromide, $\mathrm{NiBr}_{2}(\mathrm{l})$ . Include the direction of the electron flow, the polarity of electrodes and the half-equations at each electrode.

Negative electrode (cathode):

Positive electrode (anode):

Figure for Answer to Question 3.2.8—Electrolytic cells question 1 — IB Chemistry SL

power source and direction of $\mathrm{e}^{-}$ movement;
labelled +/positive electrode/anode and -/negative electrode/cathode and (molten) electrolyte/ $\mathrm{NiBr}_{2}(\mathrm{l})$ ;
Accept polarity of electrodes given at the power source.

Award [1 max] for M3 and M4 if equations are given at wrong electrodes. Ignore state symbols and reversible sign.
Allow e instead of $e^{-}$ .

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3.2.8—Electrolytic cells question 1