This question is about the industrial extraction of calcium metal and bromine gas through the electrolysis of molten calcium bromide (CaBr2\text{CaBr}_2CaBr2).
Calcium is deposited at the negative electrode. Describe what happens to calcium ions (Ca2+\text{Ca}^{2+}Ca2+) during this process in terms of electrons.
Write a balanced half-equation to represent the formation of bromine molecules (Br2\text{Br}_2Br2) at the positive electrode from bromide ions (Br−\text{Br}^-Br−).
The overall chemical equation representing this electrolysis process is:
CaBr2→Ca+Br2 \text{CaBr}_2 \rightarrow \text{Ca} + \text{Br}_2 CaBr2→Ca+Br2Determine the mass, in kg\text{kg}kg, of bromine gas generated when 500 kg500\text{ kg}500 kg of molten calcium bromide is completely decomposed.
Relative atomic masses (ArA_rAr): Ca=40\text{Ca} = 40Ca=40; Br=80\text{Br} = 80Br=80
12 exam-style questions on AQA GCSE Chemistry 4.3 Electrolysis, covering 4.3.1 The process of electrolysis, 4.3.2 Electrolysis of molten ionic compounds, 4.3.3 Using electrolysis to extract metals, 4.3.4 Electrolysis of aqueous solutions, and 4.3.5 Representation of reactions at electrodes as half equations (HT only). Each one has a worked solution and a mark scheme showing where the marks go.