Edexcel IGCSE Chemistry 2.7 halogen displacement reactions
Practise halogen-displacement questions by using reaction tables, predicting whether displacement occurs and writing equations.
- Syllabus
- First assessment 2019
- Course
- Chemistry 4CH1
Practise halogen-displacement questions by using reaction tables, predicting whether displacement occurs and writing equations.
This question is about Group 7, the halogens.
When a halogen is added to a solution containing halide ions, a displacement reaction may occur.
The table shows whether a reaction occurs.
Using information from the table, explain the order of reactivity of the three halogens.

An explanation linking the following three points:
- chlorine displaces bromine and iodine / reacts with bromide and iodide ions
- bromine displaces iodine / reacts with iodide ions; iodine does not displace chlorine or bromine / does not react with chloride or bromide ions
- order of reactivity: chlorine > bromine > iodine
Allow:
- chlorine has two reactions
- iodine has no reactions
- chlorine is most reactive and iodine is least reactive
- reactivity decreases down the group
Marking guidance:
- Deduct 1 mark only for incorrect use of -ide or -ine.