How many grams of KClO3 are needed form 21.9g of O2

Question

How many grams of  are needed to form  of KClO_{3 are needed to form 21.9g of O2}

Answer 1

Write a correctly balanced equation for the reaction:

2KClO₃ ==> 3O₂ + 2KCl

moles of O₂ desired = 21.9 g O₂ x 1 mole/32.0 g = 0.684 moles O₂

moles KClO₃ needed = 0.684 moles O₂ x 2 moles KClO₃/3 moles O₂ = 0.456 moles KClO₃ needed

grams KClO₃ needed = 0.456 moles KClO₃ x 122.55 g/mole = 55.9 grams KClO₃ needed