Stoichiometry question

Question

How many grams of potassium chlorate must decompose to form 40.0 grams of oxygen? The other product of the decomposition is potassium chloride. (Write an equation)

Answer 1

Potassium chlorate = KClO₃

Balanced equation: 2KClO₃ ===> 2KCl + 3O₂

moles O₂ needed = 40.0 g O₂ x 1 mole/32 g = 1.25 moles O₂ needed

According to the balanced equation, we can find moles of KClO3 needed to produce this amount of O2...

1.25 moles O₂ x 2 moles KClO₃ / 3 moles O₂ = 0.8333 moles KClO₃ needed

Converting this to grams, we have...

0.8333 moles KClO₃ x 122.6 g/mole = 102 grams KClO₃ (to 3 sig. figs.)