A 2.00 M solution of CaCl2 in water has a density of 1.17 g/mL. What is the mole fraction of CaCl2?

Answer 1

2.00 M CaCl2 means 2 moles CaCl2/L solution. 1 L of solution has a mass of
1.17 g/mL x 1000 mL = 1170 grams.
How much of that is water?
1170 - grams of CaCl2.
Convert grams of water to moles.
Then moles fraction CaCl2 = moles CaCl2/total moles.

Answer 2

0.380