What volume of oxygen will be released during the thermal decomposition of 245 g of berthollet’s salt?

The reaction equation for the thermal decomposition of potassium chlorate (berthollet’s salt):

2KClO3 (t, cat.) = 2KCl + 3O2

Amount of potassium chlorate substance:

v (KClO3) = m (KClO3) / M (KClO3) = 245 / 122.5 = 2 (mol).

According to the reaction equation, 3 mol of O2 is formed per 2 mol of KClO3, therefore:

v (O2) = v (KClO3) * 3/2 = 2 * 3/2 = 3 (mol).

Thus, the released volume of oxygen, measured under normal conditions (n.o.):

V (O2) = v (O2) * Vm = 3 * 22.4 = 67.2 (l).

Answer: 67.2 l.