Question

onsider the following unbalanced chemical equation for the reaction which is used to determine blood alcohol levels: H1+ + Cr2O72- + C2H6O → Cr3+ + CO2 + H2O In the forward reaction, is chromium oxidized and/or reduced?

Answer 1

Answer:

Chromium is reduced in forward reaction

Explanation:

A species is said to be oxidized if oxidation number of the species increases.

A species is said to be reduced if oxidation number of the species decreases.

Oxidation number of Cr in $Cr_{2}O_{7}^{2-}$ = +6

Oxidation number of Cr in $Cr^{3+}$ = +3

So change in oxidation number of Cr in forward reaction = (+3)-(+6) = -3

Hence oxidation number of Cr decreases on going from  $Cr_{2}O_{7}^{2-}$ to  $Cr^{3+}$.

So, chromium is reduced in forward reaction.