Question

An aqueous salt solution is formed by adding 11.67 g sodium sulfate (solute) to water (solvent). What mass (in g) of water is used if the freezing point of the solution is -12.9 Farenheit.

Kf H2O = 1.86 Celsius/m

Answer 1

Convert -12.9 F to C and calculate delta T for H2O.

delta T = i*Kf*m
i = 3, solve for m

m = # moles Na2SO4/kg solvent
You know m and # moles, solve for kg solvent.

Answer 2

How do you calculate delta T for H2O?

Answer 3

delta T is the change in temperature
final temperature-initial temperature

Answer 4

Did you convert -12.9F to C? I obtained -24.9C so the difference between -24.9C and 0C is 24.9
Then 24.9 = 3*Kf*m