Thanks you have made it more clear now but how does the second mark relate about the electrode potential for sulphate ion is bigger than Br-
The mark scheme says that the elctrode potential for sulphate ions is smaller (not bigger) i.e. less positive, so it wont be the best one at taking in electrons (going forward). The Br2/Br- electrode is more positive so that is the best at taking electrons in (going forward)
The mark scheme says that the elctrode potential for sulphate ions is smaller (not bigger) i.e. less positive, so it wont be the best one at taking in electrons (going forward). The Br2/Br- electrode is more positive so that is the best at taking electrons in (going forward)