Determining the voltage of a cell Setup: A magnesium electrode dipped in a magnesium sulfate solution and an iron electrode dipped into iron (III) sulfate solution

Am I right in thinking that you need to first identify the redox reactions to determine to determine overall voltage of the cell at standard conditions?

I have identified Mg to be oxidized to Mg(2+) at the anode, but I am not sure which is reduced at the cathode. Would it be the sulfate ions?

If it is indeed the sulfate ions, I have calculated the standard electrode potential to be 2.54 volts (is this correct)?
[...] I am not sure which is reduced at the cathode. Would it be the sulfate ions?


orthocresol has already pointed out in his comment that there's more in $\ce{Fe2(SO4)3}$ than just the sulfate.

Take a look at the cation:

$$\begin{align}
\ce{Fe^3+&amp; + e- &amp;&lt;=&gt;&amp;Fe^2+\quad &amp;+0.77V} \\
\ce{Fe^3+&amp; + 3e- &amp;&lt;=&gt;&amp;Fe(s)\quad &amp;-0.04V}
\end{align}$$

(Standard electrode potentials are cited from wikipedia.)