Question

please please please help me balance these two equations...

1. K2Cr2O7+H2C2O4.2H2O--> K[Cr(H20)2(C2O4)2].2H2O+CO2

2. K2Cr2O7+H2C2O4.2H2O--> K[Cr(H20)2(C2O4)2].3H2O+CO2

Answer 1

There are rules to follow in balancing redox equations. Here are the rules.
http://www.chemteam.info/Redox/Balance-HalfReactions-Acid.html

Here are some helpful hints.
#1. Both Cr change from +12 on the left to +6 on the right(FOR TWO Cr ATOMS on the right).
C changes from +6 on the left for both C atoms to +8 on the right for TWO C ATOMS of C in CO2. Note also that the C2O4 that is complexed with the Cr on the right does not undergo oxidation.

Answer 2

Common we need an example, its complexed. It doesnt change from 12 -6 it goes from 6-3 and carbon goes from 3-4. If the half reactions have to = the entire reaction then how is broken down. This is why students get irritated with posts like this. They know you wont be able to figure it out on your own.