Help with GCSE Chemistry please!?

Question

My question is ; What mass of calcium chloride is produced from 2 grams of calcium carbonate?

I know that I have to write down the 2 formulas which would be Calcium Chloride > CaCl2 and Calcium Carbonate CaCO3, and then add up there relative atomic masses and add them up, they then should be equal, but when I add them up Calcium Chloride ends up as 112g and Calcium Carbonate 100g. They need to be equal can anyone tell me where im going wrong? Thanks :)

I just reliased Im using the wrong way to solve it, as that is for calculating the mass of the product but now im totally confused, can someone explain to me how to do it? thanks

Answer 1

What needs to be equal is the number of MOLES CaCl2 and CaCO3. This is because in the balanced equation

CaCO3 + 2HCl = CaCl2 + CO2 + H2O

one CaCO3 gives you just one CaCl2. (Actually you don't even need the equation, if you just think about the number of calciums)

2 g CaCO3 at 100 g per mole gives you 0.002 moles.

So all you need to do now is to find the weight of that number of moles CaCl2, and you have done.

Answer 2

They dont need to be equal, in fact that's the point.
if 100g Calcium Carbonate makes 112g Calcium Chloride, then 2g will make 2.24g Calcium Chloride. Its just the ratio of reactant to product