What is the greatest amount of cao (in moles) that can be made with 3.9 moles of ca 2.35 moles of o2.
which is the greatest reactant?
which reactant is a excess and how many grams age left over.

Explanation:

The equation for this chemical reaction is:

2Ca + O2 -> 2CaO

So 2 moles of Ca react with 1 mole of O2 to form 2 moles of CaO.

Given 3.9 moles of Ca and 2.35 moles of O2,

Ca is the greater reactant as it will be used up.

O2 is the reactant in excess and there will be 2.35 - 3.9/2 = 0.4 moles left.

As mass of 1 mole of O2 is 32g, 0.4 moles of O2 = 0.4 * 32 = 12.8g

Moles of CaO formed = moles of Ca = 3.9

As mass of 1 mole of O2 is 56g, 3.9 moles of CaO = 3.9 * 56 = 218.4g of CaO

do you need with anything?