limiting reagants gcse chem

You can see the ratio of reactants given in the equation; 1 mol O2 gives 2 mol CaO.

So try multiplying up everything by 2 (as you’re given 2 mols O2 to react), which gives 4Ca 2O2 —> 4CaO. As you’ve used all your moles of O2, O2 is the limiting reagent. And you can see how much product from the equation.

You can verify that O2 is the limiting reagent by multiplying up the equation by 5, to use all of the Ca given. This is: 10Ca 5O2 —> 10CaO. You can see that you’re using more moles of O2 than you have, so O2 must be the limiting reagent.

ohh ok so how would you use this info to find the number of moles in CaO?

Once you’ve multiplied up the equation to find the limiting reagent (in this case the equation becomes 4Ca 2O2 —> 4CaO), you can see you’re using all the available moles of O2. Therefore you must be making 4 moles of CaO, as the whole equation has been multiplied to reflect how much of the limiting reagent you have.

Try to understand how to get to the answer rather than writing it down - it will help you more in the long run!

ok thank you so much i appreciate the help!!