Question

If you had dehydrated 1.00g of the hydrate CaCl2 ∙6H2O how many grams of anhydrous CaCl2 would you expect to be produced? Show calculations.

I really am having a hard time with this question. I don't know where to start and how to perform it.

Answer 1

There's the long way, a shorter way, and a short cut that isn't taught in schools anymore.
Long way.
mols CaCl2.6H2O = grams/molar mass = ?
mols CaCl2 = mols CaCl2.6H2O since there is 1 mol CaCl2 in 1 mol CaCl2.6H2O
Finally, g CaCl2 = mols CaCl2 x molar mass CaCl2.

shorter way.
% CaCl2 in CaCl2.6H2O = (molar mass CaCl2/molar mass CaCl2.6H2O)*100 = ?
Then 1 g*(%CaCl2/100) = ?g CaCl2.

Shortcut way not taught now.
1 g x (molar mass CaCl2/molar mass CaCl2.6H2O = ?g CaCl2.