Suppose you added 4.000 g of FP sample #1 instead of 2.000 g, what would happen
ID: 1050505 • Letter: S
Question
Suppose you added 4.000 g of FP sample #1 instead of 2.000 g, what would happen to the freezing point temperature of the water?
A.The freezing point would be depressed twice as much.
B.The freezing point would be increased twice as much.
C.There is not enough information to calculate the freezing point depression.
D.The freezing point would be depressed half as much.
Suppose you dissolve 154.286 g of sodium chloride in 2.00 L of water. What is the molality of the solution given that the molar mass of sodium chloride is 58.44 g/mol and the density of water is 1.000 g/mL?
Explanation / Answer
1)
A) The freezing point would be depressed twice as much.
here
delta Tf = Kf x m
0 - Tf = Kf x m
Kf is constant. so it is directly proportional to molality.
2)
moles of sodium chloride = 154.286 / 58.44 = 2.64
mass of water = 2 x 10^3 mL = 2000 g = 2 kg
molality = moles of solute / mass of solvent in kg
= 2.64 / 2
molality = 1.32 m