Complete and balance the following half-reaction in basic solution

Question

Cr(OH)_3(s) --> CrO₄^2-_(aq)

Answer 1

Cr(OH)_3(s) ===> CrO₄^2-_(aq) (note: Cr goes from ox.no. 3+ to ox. no. 6+, so 3 electrons will be involved)

Cr(OH)₃ + H2O ===> CrO₄^2- ... to balance oxygens

Cr(OH)₃ + H2O ===> CrO₄^2- + 5H+ ... to balance hydrogens

Cr(OH)₃ + H2O + 5OH- ===> CrO₄^2- + 5H⁺ + 5OH- ... because it is in basic solution

Cr(OH)₃ + H2O + 5OH- ===> CrO₄^2- + 5H⁺ + 5OH- + 3e- ... to balance charge

Cr(OH)₃ + 5OH- ===> CrO₄^2- + 4H2O + 3e- BALANCED FOR MASS AND CHARGE