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### Final 2013 Q3A

Posted: Mon Mar 13, 2017 11:26 pm
Given the redox reaction: $HClO_2(aq) + Cr^+3 _(aq) \rightarrow HClO_(aq) + Cr_2O_7 ^-2 _(aq)$
We are asked to write the two half reactions and balanced equation for the above redox reaction. Just to be sure, do we balance the equation after writing the half reactions because we have to add H^+ and H2O to the half reactions?

### Re: Final 2013 Q3A

Posted: Mon Mar 13, 2017 11:32 pm
Correct!

Step 1: Write and balance the two half reactions individually
Step 2: Make sure each half reaction has the same number of electrons. If not, multiply one or both reactions so that the number of electrons cancel.
Step 3: Add the two half reactions. *If the half reactions were balanced correctly with the number of electrons, then by just adding the two half reactions, you should already get a properly balanced overall reaction.

### Re: Final 2013 Q3A

Posted: Mon Mar 13, 2017 11:41 pm
That makes it so clear! Thank you

### Re: Final 2013 Q3A

Posted: Thu Mar 16, 2017 11:21 pm
I am confused on finding the Ecell value: they would have to give us each half-reaction cell potential but then how do we determine which is for the anode and which is for the cathode??