Predicting directions of redox reactions [closed]








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Hello! 


In this textbook example question, how come the chlorine reaction, which has the greatest reducing power will not react? If it has the greatest E of 1.36 V that means it has most reducing stength and can "pull" electrons from both the Br and I reactions. In my mind I believed it would do so, and since the I-reaction has an even lower E than the Br-reaction the extent of oxidation would be greater for I. But in the answer they say the direct opposite, that Cl does not react and Br will only oxidize I. 


Why does Cl which is the strongest oxidizing agent not do anything in this case? 




Because in the original question there is no elemental chlorine present. It says that you start from a solution of chloride and iodide, so both ions that can be oxidized to the corresponding halogen. And the rest of the answer is already given in your textbook example. Chlorine is a much stronger oxidizing agent. This means that it oxidizes others very well. But what you've got is bromine, and bromine is just between chlorine and iodine, so it can oxidize iodide to iodine but not chloride to chlorine. I think you got confused with the direction and the redox-terms here a bit. 


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