29. An isotonic solution contains 0.94% NaCl by mass per volume. Calculate the p

Question

29. An isotonic solution contains 0.94% NaCl by mass per volume. Calculate the percent mass per volume for isotonic solutions containing each of the following solutes at 25?C. Assume a van't Hoff factor of 1.9 for all ionic solutes.

A. KCl

B. NaBr

C. Glucose

31. A solution of a nonvolatile solute in water has a boiling point of 376.0K .

A. Calculate the vapor pressure of water above this solution at 338 K. The vapor pressure of pure water at this temperature is 0.2467 atm

32. A solution of 49.5% H2SO4 by mass has a density of 1.39 g/cm3 at 293 K. A 25.6cm3 sample of this solution is mixed with enough water to increase the volume of the solution to 99.0cm3 .

A. Find the molarity of sulfuric acid in the obtained solution.

33. A solution contains 11.00g of unknown compound dissolved in 50.0 mL of water. (Assume a density of 1.00 g/mL for water.) The freezing point of the solution is -3.46?C. The mass percent composition of the compound is 60.98% C, 11.94% H, and the rest is O.

A. What is the molecular formula of the compound?

Explanation / Answer

A) 0.94 %

B) 0.94 %

C) 1.88 %

31)

376 - 373 = 3 = 0.512 x m

=> m = 5.86

Mole fraction of solute = 5.86 / ((1000/18) + 5.86) = 0.0954

Vapor pressure = 0.2467 x (1 - 0.0954) = 0.2232 atm

32)

Mass of 25.6 cm3 solution = 1.39 x 25.6 = 35.584 g

Mass of H2SO4 in it = 0.495 x 35.584 = 17.614 g

Vol = 99 cm3 = 99 mL

Moles of H2SO4 = 17.614 / 98 = 0.1797

Molarity = 0.1797 / 0.099 = 1.816 M

33)

3.46 = 1.86 x m

=> m = 1.86

m = (11/M) / 0.05 = 1.86

=> M = 118.3

Emperical formula

C = 60.98 / 12 = 5.08 = 5

H = 11.94 / 1 = 11.94 = 12

O = 27.08 / 16 = 1.7

C = 5 x 1.176 = 6

H = 12 x 1.176 = 14

O = 1.7 x 1.176 = 2

=> Molecular wt = 72 + 14 + 32 = 118

Molecular formula = C6H14O2

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.