Chemistry
posted by Nick .
Given the following equation:
2KClO3> 2KCl+3O2
How many moles of O2 can be produced by letting 12.00 moles of KClO3 react?

Here is a worked example. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html 
Molar Mass of KCLO3 (potassium chlorate)= 39.10+35.45+3(16.00)=122.55
First use what you are given, then use the mole to mole ratio to cancel out moles KClO3 and multiply keeping mol O2.
(12.00 moles KClO3)x(3 mol O2/2 mol KClO3) =18 moles O2
:D 
if you had 12 moles, just use a simple ratio (called a molar ratio):
12 mol KClO3 * (3 mol O2)/(2 mol KClO3) = 18 mol O2 ... this is your answer!