Potassium nitrate when exposed to heat decomposes to potassium oxide and gaseous nitrogen and oxygen

Question

Potassium nitrate when exposed to heat decomposes to potassium oxide

and gaseous nitrogen and oxygen:

4KNO3(s) -> 2K2O(s) + 2N2(g)+502(g)

To produce 28.3 g of oxygen, how many (a) moles of KNO3 and (6) grams

of KNO3 must be heated?

Answer 1

4KNO₃(s) ==> 2K₂O(s) + 2N₂(g) + 5O₂(g) ... balanced equation for decomposition of KNO₃

Use dimensional analysis:

(a) 2.83 g O₂ x 1 mol O₂ / 31.98 g x 4 mol KNO₃ / 5 mol O₂ = 0.0708 moles

(b) 0.0708 mols KNO₃ x 101.1 g / mol = 7.158 moles KNO₃ = 7.16 g KNO₃