3C - The Halogens and displacement reactions

    1)           State and explain the states of the halogens down Group 7:  [3]


    2)          This question is about the colours of the Halogens.

                    a)  Complete the table below putting in the colours of the Halogens when dissolved in

                         water and a non polar solvent [6]



Colour in water

Colour in non - polar solvent











                    b)  Explain why the colours of chlorine and bromine become more intense

                         when dissolved in a non polar solvent   [2]


    3)          This question is about the displacement reactions of the halogens.

                    a)  Copy and complete the following table as if the displacement reactions were carried out

                         using aq solutions.  Put starting and final colours in the table [6]



Potassium Chloride

Potassium Bromide

Potassium Iodide














                    b)  Write balanced chemical reactions for each of the reactions in the table above, include state symbols [6]


                    c)    The colour change in the reaction between bromine and potassium iodide is sometimes unclear

                           as bromine and iodine have similar colours when dissolved in water. 

                           What could you add to the test tube to confirm that the colour is from iodine and not bromine?

                           State the change in colour you would observe.  [2]


    4)           Chlorine is added to water as a bleach to kill bacteria. 

                    a)    Write a balanced chemical equation for the reaction between chlorine and water:  [2]


                    b)    Assign oxidation numbers to chlorine in (a):  [3]


                    c)    Use your answers to (a) and (b) to describe what type of reaction this is:  [3]