Displacement reactions involving the halogens
4 marks · NormalA student investigates halogen displacement reactions.
Describe what the student would see when bromine solution is added to potassium chloride solution.
Explain your answer to part (a).
Write a balanced equation for the reaction (if any) between iodine solution and potassium bromide solution.
State the order of reactivity of chlorine, bromine and iodine.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) No change or no colour change
(b) Bromine is less reactive than chlorine and cannot displace it from potassium chloride.
(c) No reaction: iodine cannot displace bromine
(d) Chlorine > Bromine > Iodine
Also accept: Part d: Accept list, e.g. Cl > Br > I
Common mistakes: Assuming a reaction for less reactive halogen; Incorrectly ordering halogens in part d
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly states no change/colour change.
B2 (b) · 1 mark · Correct explanation: bromine is less reactive than chlorine.
B3 (c) · 1 mark · States no reaction, with optional brief explanation.
B4 (d) · 1 mark · Correct order: Chlorine > Bromine > Iodine.
Worked solution
(a) No change is seen; the solution stays orange.
(b) Bromine is less reactive than chlorine and cannot displace it from solution.
(c) No reaction. Iodine is less reactive than bromine so cannot displace it.
(d) Reactivity order: Chlorine > Bromine > Iodine