Redox Reactions Question 2

\ce{MnO4- + 5Fe^{2+} + 8H+ -> Mn^{2+} + 5Fe^{3+} + 4H2O}

In the reaction represented above, the number of $\ce{MnO4-}$ ions that react must be equal to which of the following?

One-fifth the number of

\ce{Fe^{2+}}

ions that are consumed

Eight times the number of

\ce{H+}

ions that are consumed

Five times the number of

\ce{Fe^{3+}}

ions that are produced

One-half the number of

\ce{H2O}

molecules that are produced

Approach

First, check that the reaction is balanced. There should be the same number of atoms for each element and the net charge of each side should be equal.

In this case, the reaction is balanced. Therefore, the ratio of $\ce{MnO4-}$ to $\ce{Fe^{2+}}$ is simply the ratio of the coefficients.