Answer:
Molar mass of unknown solute is 679 g/mol
Explanation:
Let us assume that the solute is a non-electrolyte.
For a solution with non-electrolyte solute remains dissolved in it -
Depression in freezing point of solution, 
where, m is molality of solute in solution and
is cryogenoscopic constant of solvent.
Here 
If molar mass of unknown solute is M g/mol then-

So, 
so, M = 679 g/mol
Caffeine has the following percent composition: carbon 49.48%, hydrogen 5.19%, oxygen 16.48% and nitrogen 28.85%. Its molecular weight is 194.19 g/mol.
Answer:
The answer to your question is: 6.8 g of water
Explanation:
Data
2.6 moles of HCl
1.4 moles of Ca(OH)2
2HCl + Ca(OH)2 → 2H2O + CaCl2
MW 2(36.5) 74 36 g 111 g
73g
1 mol of HCl ---------------- 36.5 g
2.6 mol -------------- x
x = (2.6 x 36.5) / 1 = 94.9 g
1 mol of Ca(OH)2 -------------- 74 g
1.4 mol --------------- x
x = (1.4 x 74) / 1 = 103.6 g
Grams of water
73 g of HCl ------------------ 36g of H2O
94.9 g ------------------- x
x = (94.9 x 36) / 73 = 46.8 g of water