Balancing redox equations

[beatulec]

I was wondering if someone could help me out with these two equations, somehow I cannot manage to balance them properly...

 

1)CrO4^2- + Fe^2+ --> Cr^3+ + Fe^3+ (in acidic solution)

 

 

2)MnO4^- + ClO2^- --> MnO2 + ClO4^- (in basic solution)

 

 

I'll really appreciate any help,

Thanks!

[Comandante]

What happend with oxygen in that first equation, it didn't disappear into the thin air did it?

By the way this question goes into homework help section.

[woelen]

Write down half reactions (e.g. CrO4(2-) + 8H(+) + 3e --> Cr(3+) + 4H2O) for all of the oxidizers and for the reductors, and then combine the oxidizer equation and reductor equation, such that the number of electrons is the same at both sides of the arrow.