When heated, potassium chlorate decomposes by the reaction:

Question

2KClO3 → 2KCl 3O2

How many liters of O2 gas result when 75.0 grams of KClO3 react at 30.0oC and 1.10 atm.?

Answer 1

As always, when converting amounts of one material to another, you go through moles and use the balanced equation.

Divide 75.0 g by the relative molar mass (g/mole) of KClO3 to get moles KClO3 (make sure you understand this step).

For every 2 mol KClO3, you get 3 mol O2 (again, make sure you understand why that is).

Now you know how many moles O2 you have, use that number as the value of n in the equation

PV = nRT

Remember to use degrees K, and at the end round down to a reasonable number of significant figures.