redox reaction help

Question

Balance the following in a basic solution. (Omit states-of-matter from your answer. Use the lowest possible whole number coefficients.)

Ti(s) + CrO₄²⁻(aq) → Ti(OH)₃(s) + Cr(OH)₄⁻(aq)

Answer 1

I like the oxidation state method of redox balancing (It's much better for OH^- environment:

Ti ⇒ Ti(OH)₃ (Which is Ti going from 0 to +3 oxidation state (after Ti's balanced))

Ti ⇒ Ti(OH)₃ + 3e^- (Provide e^- in order to change oxidation states)

Ti + 3OH^- ⇒ Ti(OH)₃ + 3e^- (Use OH^- to balance charges - all set for ox. 1/2-rxn)

CrO₄^2- ⇒ Cr(OH)₄^- (Cr is going from +6 to +3)

CrO₄^2- + 3e^- ⇒ Cr(OH)₄^- (again, provide electrons for Ox State change)

CrO₄^2- + 3e^- ⇒ Cr(OH)₄^- + 4OH^- (Balance charge with OH^-)

4H₂O + CrO₄^2- + 3e^- ⇒ Cr(OH)₄^- + 4OH^- (Use H₂O to balance O, and H balance can be used as a check)

Now, just add the half-reactions as they are to cancel electrons. Fix OH^- so that it is only on one side.

Please consider a tutor. Take care.