Question

9) H ow many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the
following reaction? The molar mass of KNO3 is 101.11 g/mol.
4 KNO3(s) ? 2 K2O(s) + 2 N2(g) + 5 O2(g)

Answer 1

This is a basic stoichiometry problem.

the molar mass of KNO3 is 101.11 g/mol, and this is used as a conversion factor.

You must also have the balanced equation to write a mol-to-mol ratio as a conversion factor; for example, for every 5 mol of O, there is 1 mol of KNO3(just from reading the balanced equation)

58.6g KNO3 x (1mol KNO3/101.11g KNO3) x (5mol O2/1mol KNO3) = 2.90 mol O2