[sun725]

Hi,

I have to write the equations for the three redox reactions in the oxidation state of vanadium.

I started by writing the half reactions, and I wonder if they're correct?

V²⁺ → V³⁺ 
VO₂⁺ → V³⁺ + H₂O 
VO²⁺ + 2H⁺ → V³⁺ + H₂O 
VO₂⁺ + 2H⁺ + e^- → V³⁺ + H₂O 

Thanks in advance

[AWK]

VO₂⁺ + 2H⁺ + e^- → V³⁺ + H₂O

Check material and charge balance

[sun725]

So it should be:

VO₂⁺ + 2H⁺ + e^- → H₂O(l) +VO²⁺(aq)

Thanks again

[AWK]

This particular reaction is correct but it has nothing common with your previous reactions.

Since almost all reactions chemist perform in water you may omit (i) and (aq) or use these symbols consequently on both side of reaction (for electrons this is unusable).

[sun725]

Okay,

I tried again and came up with this:

e^-+2H⁺+VO₂⁺ VO²⁺+H₂O

[AWK]

This is the same reaction as previously (more consistent, since without additional symbols).
THe first your reaction was:

V²⁺ → V³⁺
 

probably V(V)
V(V)  V(III)
then
VO₂⁺  VO⁺

and finally you presented reaction for
V(V)  V(IV)