Calculate the mass of O2 produced if 3.450 g potassium chlorate is completely decomposed by heating in presence of a catalyst (manganese dioxide)

The reaction is:

2 KClO3 (s) → 3 O2 (g) + 2 KCl (s)

A catalyst simply lowers the activation energy so MnO2 is not part of the overall reaction.

By stoichiometry:

3.45 g KClO3 x 1 mol / 122.55g KClO3 x 3 mol O2 / 2 mol KClO3 x 31.99g / 1 mol O2 = 331.096 / 245.1 = 1.35 grams O2 produced

Answer:

1.35 grams O2