Calculate the mass of berthollet’s salt required to obtain a 40 g portion of oxygen.

To solve, we write down the reaction equation:
2KClO3 = 3O2 + 2KCl – decomposition reaction of berthollet salt, oxygen is released;
We calculate the molar masses of substances:
M (KClO3) = 112.6 g / mol;
M (O2) = 32 g / mol;
Determine the amount of moles of oxygen by the formula:
Y (O2) = m / M = 40/32 = 1.25 mol.
According to the equation, we will compose the proportion:
X mol (KClO3) – 1.25 mol (O2);
-2 mol -3 mol from here, X mol (KClO3) = 2 * 1.25 / 3 = 0.83 mol.
Find the mass of KClO3:
m (KClO3) = Y * M 0.83 * 122.6 = 101.75 g.
Answer: the mass of the berthollet salt is 101.75 g.