J.R. S. answered 06/28/22
Ph.D. University Professor with 10+ years Tutoring Experience
2KClO3 ==> 2KCl + 3O2
At STP, 1 mol of any ideal gas occupies 22.4 L (memorize this value)
So, how many moles of O2 are formed from 10.0 g of KClO3?
molar mass KClO3 = 122.5 g / mol
molar mass O2 = 32 g / mol
mols KClO3 used = 10.0 g x 1 mol / 122.5 g = 0.0816 mols KClO3
mols O2 produced = 0.0816 mols KClO3 x 3 mols O2 / 2 mols KClO3 = 0.1224 mols O2 produced
Liters of O2 = 0.1224 mols x 22.4 L / mol = 2.74 L O2 @ STP