A solution of 2g in 50g of another solution freszes at 1.05 degrees celcious. What is the MOLAR MASS of this substance?
2007-07-14 04:13:25 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
What is the solvent?
I make calculus for water (1 liter of water =1000g)
2g in 50g corresponds to 2*1000/50 = 40g/Liter
the molarity of the solution is (if non electrolyte!)
1.05/1.86 = 0.565M
so 40g = 0.565M
the molar mass is 40/0.565 =71g
2007-07-14 04:22:30 · answer #1 · answered by maussy 7 · 0⤊ 0⤋
You first use the freezing point depression equation to determine the molality. Then you divide by 20 because you have 1/20 of a kg of solvent. That's the number of moles you have dissolved. Take 2 g divided by that number of moles and that gives you the molecular weight in grams per mole.
2007-07-14 11:23:45 · answer #2 · answered by Fly On The Wall 7 · 0⤊ 0⤋