What is the freezing point of a solution of glucose, a nonelectrolyte, that cont

Question

What is the freezing point of a solution of glucose, a nonelectrolyte, that contains 40.0 g of C6H12O6 dissolved in 425 g of water? Use molar masses with at least as many significant figures as the data given.

=____°C

What is the boiling point of the solution?=____ °C

What is the freezing point of a solution of calcium chloride that contains 60.0 g CaCl2 dissolved in 435 g of water, answer should be significant to 0.01's place? Use molar masses with at least as many significant figures as the data given.
°C
What is the boiling point of the solution, answer should be significant to 0.01's place?
°C

Explanation / Answer

dT = K*m

m = mol solute / Kg solvent

mol of C6H12O6 = mass/MW = 40/180 = 0.222 mol of glucose

kg solvent = m/1000 = 425/1000 = 0.425 kg

m = 0.222 /0.425 = 0.522 molal

dT = K*m

dT = 0.522*1.86 = 0.97092 °C

T = 0-0.97092 = -0.97 °C

Boiling point

dT = +Kb*m = 0.512*0.522 = 0.26726 °C

Tb = 100 + dT = 100 + 0.26726 = 100.267 °C

This is pretty similart, but the exception is

CaCl2 --> Ca+2 and 2Cl-there are 3 ions instead of 1

dT = 3*K*m

m = mol/kg

mol = mass/MW = 60/110.98 = 0.5406

kg = 0.435

then m = 0.5406/0.435 = 1.24275

dT = 3*K*m

dT = 3*1.86*1.24275 = 6.93

freez = 0

T = 0-6.93 = -6.93°C

boil

dT = 3*K*m

dT = 3*0.512*1.24275 = 1.91

Tb = 100 + 1.91 = 101.91°C

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