- #1
steven10137
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Homework Statement
http://img143.imageshack.us/img143/7135/electrolysisrf2.jpg
What is the ratio of number of moles of copper deposited to the number of moles of mercury deposited? {n(Cu):n(Hg)}
2. The attempt at a solution
Well the species present are;
[tex]
\begin{array}{l}
Cu^{2 + } /SO_4 ^{2 - } \;ions \\
Hg_2 ^{2 + } /NO_3 ^ - \;ions \\
and\;H_2 O \\
\end{array}
[/tex]
so reading down the Eo table from left to right; the first species found is [tex]Cu^{2 + }[/tex] ions.
So at the cathode we have; [tex]Cu^{2 + } + 2e^ - \to Cu[/tex]
Now reading up the Eo table from right to left; the first species found is [tex]Hg_2 ^{2 + }[/tex]
So I would assume that at the anode we have; [tex]Hg_2 ^{2 + } \to 2Hg^{2 + } + 2e^ - [/tex]
Now the question states that it is the ratio of copper to mercury produced. How can this be?
Do I just assume that the mercury ions are now further electrolysed to mercury by;
[tex]Hg^{2 + } + 2e^ - \to Hg_{(l)}[/tex]
Could someone please explain how this works and what rules I am supposed to be following as I am a little confused ...
cheers
Steven
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