Question

Which one is the limiting reactant if 0.0453 moles of sodium carbonate was used and 0.0216 moles of calcium choloride was used?

Balanced Eq. Na2CO3 + CaCl2 = CaCO3 + 2NaCl

Answer 1

Na2CO3 + CaCl2 = CaCO3 + 2NaCl

Yes, the first step is to write a balanced equation of the reaction.
The coefficients of the balanced equation tells us the relative number of moles of each reactants is required, as well as the relative number of moles of the products.

In this example, the relative number of moles are:
1* Na2CO3
1* CaCl2
1* CaCO3
2* NaCl

This means that Na2CO3 and CaCl2 are in the ratio of 1:1.
If 0.0453 mol of Na2CO3 were used, it will require 0.0453 mol of CaCl2, which is greater than the supplied 0.0216 mol of CaCl2 available.

Would you be able to figure out the limiting reagent?

Note:
Limiting reagent is defined as:
<i>The limiting reagent (or limiting reactant) in a chemical reaction is the substance that is totally consumed when the chemical reaction is complete.</i>

Answer 2

It would be CaCl2

Answer 3

How do I find theoretical amount that should have formed or CaCl2?

Answer 4

Yes, the limiting reactant is CaCl2.
Since it is a reactant, there is no new CaCl2 formed... unless you meant something else.
The same idea extends to products.
The overall molecular ratios are 1:1:1:2. So you can calculate amounts of products formed using the ratio.