Good work. You recognize that this is a red-ox reaction. And you know some additional reactions the KI-I2 system has. Now, you have to consider if SO2 has sufficient reducing power to affect the KI salt.
I am sure that SO
2 has sufficient reducing power to affect the I
2.
Of course, It is taken for granted that reducing power of SO
2 cannot make KI deoxdized.
However, as i mentioned above, SO
2 is an oxidizing agent in some cases. For example, when SO
2 meets H
2S, this reaction happens: 2H
2S+SO
2→3S+2H
2O
Obviously, SO
2 works as an oxidizing agent.
Therefore, I want to know whether SO
2 has sufficient oxidizing power to affect I
-.