Use the van\'t Hoff factors in the table below to calculate each colligative pro

Question

Use the van't Hoff factors in the table below to calculate each colligative property:

Table. Van't Hoff Factors at 0.05 m Concentration in Aqueous Solution

Part A

Calculate the melting point of a 0.118 m iron(III) chloride solution.

-0.746

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Part B

Calculate the osmotic pressure of a 8.9×102 M potassium sulfate solution at 307K.

Express your answer using two significant figures.

Part C

Calculate the boiling point of a 1.42 % by mass magnesium chloride solution.

Solute /Expected /Measured Nonelectrolyte 1 1 NaCl 2 1.9 MgSO4 2 1.3 MgCl2 3 2.7 K2SO4 3 2.6 FeCl3 4 3.4

Explanation / Answer

PART B :

Osmatic pressure = i x MST

M = molarity = 8.9×102 M

S = universal gas constant = 0.0821 L-atm/mol-K

T = temperature = 307

i = Van't Hoff Factor = 2.6

P = i x M x S x T

   = 2.6 x 8.9×102 x 0.0821 x 307

   = 5.83 atm

osmatic pressure = 5.83 atm

PART C:

Moles MgCl2 = 1.42g / 95.211 g/mol =0.0149

Mass water = 100 - 1.42 = 98.58 g = 0.09858 Kg

molality = 0.0149 / 0.09858 =0.1511 m

delta T = i x Kb x m

              = 2.7 x 0.52 x 0.1511

               = 0.212

Tb -To = 0.212

Tb - 100 = 0.212

Tb = 100.212oC

boiling point = 100.212 °C

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