Electrolysis of Molten Compounds Flashcards

All 6 cards in this deck

What are the steps to predict the products of electrolysis of a molten binary ionic compound?

e.g. molten zinc chloride

1. Identify the ions: $\mathrm{Zn^{2+}}$ and $\mathrm{Cl^-}$
2. Cation goes to the cathode: zinc at the cathode
3. Anion goes to the anode: chlorine at the anode

What are the products of the electrolysis of molten lead bromide?

Lead at the cathode and bromine at the anode.

What is the half equation at the cathode in the electrolysis of molten lead bromide?

$\mathrm{Pb^{2+} + 2e^- \rightarrow Pb}$

What is the half equation at the anode in the electrolysis of molten lead bromide?

$\mathrm{2Br^- \rightarrow Br_2 + 2e^-}$

Why must an ionic compound such as lead bromide be melted before it can be electrolysed?

Melting frees the ions to move, so the compound can conduct and be decomposed.

True or false? Electrolysis of molten potassium bromide produces hydrogen at the cathode.

False. Potassium is produced at the cathode; there is no water, so there are no hydrogen ions.