## Final 2013 Q3A

Stephanie_Thai_2C
Posts: 10
Joined: Fri Jul 22, 2016 3:00 am

### Final 2013 Q3A

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?

Jonathan Sarquiz 3F
Posts: 32
Joined: Fri Jul 15, 2016 3:00 am

### Re: Final 2013 Q3A

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.

Stephanie_Thai_2C
Posts: 10
Joined: Fri Jul 22, 2016 3:00 am

### Re: Final 2013 Q3A

That makes it so clear! Thank you

Simone Seliger 1C
Posts: 30
Joined: Fri Sep 25, 2015 3:00 am

### Re: Final 2013 Q3A

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??