What is the minimum mass of glycerol (C3H8O3) that must be dissolved in 18.0 mg water to prevent the solution from freezing at -30°C? (Assume ideal behavior.)
2006-09-06 07:47:05 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
If we assume ideal behaviour, we want the amount of glycerol that will decrease the freezing point by 30 C.
If m is the molality of such a solution then
dTf= Kf*m
for water Kf=1.858
Thus 30=1.858m => m=30/1.858 =16.15 moles /1000 g water or 16.15 moles /10^6 mg of water
so for 18 mg of water you need (16.15/10^6)*18 moles of glycerol
and mass=moles*MW= (16.15/10^6)*18 *92=0.0267 g glycerol
2006-09-06 09:09:26 · answer #1 · answered by bellerophon 6 · 1⤊ 0⤋
well in theory the resolute formula of glycerol is typically 6.8% of the gram formula mass so by dividing this by pie we work out that i really dont have a f**king clue what i am talking about and i just want to say ..
GET A LIFE NERD!!
p.s. thanks for the two points yaaaaaaaaaaaasssssssss
2006-09-06 08:11:36 · answer #2 · answered by Anonymous · 0⤊ 1⤋