I'm doing a question on combining two half equations to form an overall cell reaction, which I did successfully. In the previous reaction Fe2+ ions catalyse the reaction with I- and thiosulfate ions. In part b of the question, the questions says why iodide and thiosulfate ions can also be catalysed by fe3+ ions?
the answer being :
Fe3+ could react with I– ions first
I don't understand- only worth one mark. just want to understand