Which is the correct oxidation half reaction for the following reaction K2Cr2O7 + H2O + S à SO2 + KOH + Cr2O3

Explanation:

Hello,

In this case, for the reaction:

We first must assign the oxidation state of each element:

Thus, we should remember that the oxidation half-reaction applies for the element undergoing an increase in its oxidation state, such case is sulfur, for which passes from 0 to +4 as shown below:

It means, that four electrons were lost due to the effect of the strong oxidizing agent, potassium dichromate.

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