How many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the following reaction? 4 KNO3 (s) → 2 K2O (s) + 2 N2 (g) + 5 O2 (g)

0.725 mol

Explanation:

Moles are calculated as the given mass divided by the molecular mass.

i. e.,

moles = (mass / molecular mass)

since,

mass of KNO₃ = 58.6 g (given)

Molecular mass of KNO₃ = 101 g / mol

Therefore,

moles of KNO₃ = 58.6 g / 101 g / mol

moles of KNO₃ = 0.58 mol

From the balanced reaction,

4 KNO₃ (s) - --> 2K₂O (s) + 2N₂ (g) + 5O₂ (g)

By the decomposition of 4 mol of KNO₃, 5 mol of O₂ are formed,

hence, unitary method is used as,

1 mol of KNO₃ gives 5 / 4 mol O₂

Therefore,

0.58 mol of KNO₃, gives, 5 / 4 * 0.58 mol of O₂

Solving,

0.58 mol of KNO₃, gives, 0.725 mol of O₂

Therefore,

58.6g of KNO₃ gives 0.725 mol of O₂.