question_answer 45)

  Thiosulphate reacts differently with iodine and bromine in the reactions given below : \[2{{S}_{2}}O_{3}^{2-}+{{I}_{2}}\to {{S}_{4}}O_{6}^{2-}+2{{I}^{-}}\] \[{{S}_{2}}O_{3}^{2-}+2B{{r}_{2}}+5{{H}_{2}}O\to 2SO_{4}^{2-}+2B{{r}^{-}}+10{{H}^{+}}\] Which of the following statements justifies the above dual behaviour of thiosulphate? (a) Bromine is a stronger oxidant than iodine. (b) Bromine is a weaker oxidant than iodine. (c) Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reactions. (d) Bromine undergoes oxidation and iodine undergoes reduction in these reactions.

Answer:

  (a) Bromine is stronger oxidising agent than iodine hence it gives different behaviour towards thiosulphate.