If the decomposition of a sample of KClO3 produces 3.29 g of O2. What was the mass (g) of the original sample?

8.41 g

Explanation:

To calculate the moles :

The balanced chemical equation for decomposition is :

According to stoichiometry :

As 3 moles of are produced by = 2 moles of

Thus 0.103 moles of are produced by =  of

Mass of

8.41 g was the mass of the original sample.