Hydrogen peroxide (H_2O_2) decomposes to form water and oxygen. How do you write the balanced equation for this reaction?

$2 {H}_{2} {O}_{2} \left(l\right) r i g h t \le f t h a r p \infty n s 2 {H}_{2} O \left(l\right) + {O}_{2} \left(g\right)$
This is in fact a disproportionation reaction in that oxygen in peroxide ($- I$ oxidation state) has given water ($- I I$ oxidation state for oxygen) and zerovalent oxygen gas ($0$ oxidation state for oxygen).
Often a $M {n}^{2 +}$ salt is added to catalyze this reaction.