IB Chemistry HL 3.2.8 Electrolytic Cells Questions
Use real HL exam questions to analyse electrolytic-cell polarity and conduction and deduce molten-salt products and equations.
- Syllabus
- First assessment 2025
- Course
- Chemistry HL
- Level
- HL
Exam points
- Identify the power supply, electrodes and electrolyte in an electrolytic cell, and show the positive anode, negative cathode, electron flow and ion movement.
- Deduce the products and balanced half-equations at the anode and cathode when a molten salt is electrolysed.
- Explain how current is conducted by electrons in the wires and by cations and anions moving through the molten electrolyte.
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IB Chemistry HL 3.2.8 Electrolytic Cells Questions question 1
[Maximum number: 2]
Magnesium is a group 2 metal which exists as a number of isotopes and forms many compounds.
Magnesium chloride can be electrolysed.
Deduce the half-equations for the reactions at each electrode when molten magnesium chloride is electrolysed, showing the state symbols of the products. The melting points of magnesium and magnesium chloride are 922 K and 987 K respectively.
Anode (positive electrode):
Cathode (negative electrode):
Anode (positive electrode):
2 Cl^- Cl_2( g)+2 e^-
Cathode (negative electrode):
Mg^2++2 e^- Mg(l)
Penalize missing/incorrect state symbols at Cl_2 and Mg once only.
Marking guidance:
Award [1 max] if equations are at wrong electrodes.
Accept Mg(g).
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