Identify change in oxidation state of oxidising agent in following redox reaction. 3 H ₃ AsO _ 3(aq) + BrO _ 3(aq) ^- Br _ (aq) ^- + 3 H ₃ AsO _ 4(aq)

Step-by-step solution

The given reaction is 3 H ₃ AsO _ 3(aq) + BrO _ 3(aq) ^- Br _ (aq) ^- + 3 H ₃ AsO _ 4(aq) Let the oxidation state of As in H ₃ AsO ₃ be x . 3(+1) + x + 3(-2) = 0 x = +3 Let the oxidation state of Br in BrO ₃^- be y . y + 3(-2) = -1 y = +5 Let the oxidation state of As in H ₃ AsO ₄ be z . 3(+1) + z + 4(-2) = 0 z = +5 The oxidation state of Br in Br ^- is -1 . The oxidation state of As increases from +3 to +5 , so H ₃ AsO ₃ undergoes oxidation and acts as a reducing agent. The oxidation state of Br decreases from +5