Question

when magnesium chlorate under goes decompostion, oxgen gas is realsed in the following reaction:
2KClO3→ 2KCl + 3O2

when 3.50 grams of potassuim chlorate is decomposed at STP, how many litters of oxgen will be produced?

Answer 1

at STP, a mol of perfect gas occupies 22.4 liters
so we need to know how many moles

How many grams in 1 mol of K Cl O3 ?
K = 39
Cl = 35.5
O3 = 16*3 = 48
---------------
mol = 122.6 grams
so
3.5 grams of KClO3 = .0286 mol
for every mol of KClO3 I get 3/2 mol of O2
so
(3/2) (.0286) = .0428 mol of O2
every mol is 22.4 liters of gas so
.0428 * 22.4 = .96 or about one liter of O2

Answer 2

I said 2KClO3

Answer 3

That is why I used (3/2)