1) Calculate the freezing point of the following solutions, assuming complete di

Question

1) Calculate the freezing point of the following solutions, assuming complete dissociation.

         c. 5.2% NaNO3 by mass (in water)

         d. Calculate the boiling point of the solution in part A, assuming complete dissociation.

                (information from part A: 0.114m K2S = -.636 degress Celsius)

          e. Calculate the boiling point of the solution in part B, assuming complete dissociation.

                 (information from part B: 19.0g of CuCl2 in 461g water = -1.71 degrees celcius)         

           f. Calculate the boiling point of the solution in part C, assuming complete dissociation.

K2S

Explanation / Answer

c)

6.5% NaNO3 by mass has
6.5 grams of NaNO3 in 100 grams of solution
so it has
6.5 g NaNO3 mixed with 93.5 grams of solvent

find moles using molar mass
6.5 g NaNO3 @84.9947 g/mol = 0.07648 moles of NaNO3
0.07648 moles of NaNO3 releases twice that = 0.15295 moles of ions ... (Na+ & NO3-)

find molality
0.15295 moles of ions / 0.0935 kg solvent = 1.636 molal solution

find freezing point drop from zero celsius
dT = C (m)
dT = 1.86C/molal (1.636 molal)
dT = 3.04

yoiur freezing point
in 2 sig figs is
-3.0 Celsius

Part A: -0.619
Part B: -2.30
Part C: -2.5
Part D: 100.170
Part E: 100.633
Part F: 100.69

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