Given the following equation:

2KClO3---> 2KCl+3O2

How many moles of O2 can be produced by letting 12.00 moles of KClO3 react?

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

How many moles of o2 can be produced by letting 12.00 moles of kclo3 decompose

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!

12.00 moles of NaClO3 will produce how many grams of o2

To find out how many moles of O2 can be produced when 12.00 moles of KClO3 react, we need to use the stoichiometry of the balanced chemical equation you provided.

According to the balanced equation:
2KClO3 ---> 2KCl + 3O2

We can see that for every 2 moles of KClO3, 3 moles of O2 are produced. Therefore, we need to set up a ratio and solve for the number of moles of O2.

The ratio can be written as:
(3 moles O2) / (2 moles KClO3)

To calculate the moles of O2 produced from 12.00 moles of KClO3, we can use the following equation:

(12.00 moles KClO3) * (3 moles O2 / 2 moles KClO3)

By canceling out the moles of KClO3, we can calculate the moles of O2:

(12.00 moles KClO3) * (3 moles O2 / 2 moles KClO3) = 18.00 moles O2

Therefore, 12.00 moles of KClO3 will produce 18.00 moles of O2.

so lets say i have 3.00 moles instead of 12.00 moles than does the equations still work if i can the number around?

Here is a worked example. Just follow the steps.

http://www.jiskha.com/science/chemistry/stoichiometry.html