Displacement reactions as redox reactions
3 marks · EasyThe table shows the results of adding halogen solutions to different potassium halide solutions.
| Halogen solution | Potassium chloride | Potassium bromide | Potassium iodide |
|---|---|---|---|
| Chlorine water | — | orange solution | brown solution |
| Bromine water | — | — | brown solution |
| Iodine solution | — | — | — |
State two observations from the table that provide evidence for displacement reactions.
Identify the halide ion displaced by chlorine water from the solutions tested.
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(a) Chlorine water turns potassium bromide solution orange and potassium iodide solution brown. · must show colour change in potassium bromide, colour change in potassium iodide
(b) Bromide ion and iodide ion (from potassium bromide and potassium iodide) are displaced by chlorine water. · must show bromide ion or iodide ion
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Marking points
B1 (a) · 1 mark · Identifies orange solution with potassium bromide as an evidence of displacement.
B2 (a) · 1 mark · Identifies brown solution with potassium iodide as an evidence of displacement.
B3 (b) · 1 mark · States bromide ion and/or iodide ion are displaced by chlorine water.
Worked solution
a) Orange solution forms when chlorine water is added to potassium bromide (evidence of displacement).
Brown solution forms when chlorine water is added to potassium iodide (another evidence).
b) The halide ions displaced are bromide and iodide ions.