Question

A)
A solution is prepared by dissolving 50.4 g sucrose (C12H22O11) in 0.332 kg of water. The final volume of the solution is 355 mL. For this solution, calculate the molarity. Express the molarity in units of moles per liter to three significant figures.

B)

Calculate the molality. Express the molality in units of moles per kilogram of solvent to three significant figures.

C)

Calculate the percent by mass.Express the percent by mass to three significant figures.

D)

Calculate the mole fraction. Express the mole fraction to three significant figures.

E)

Calculate the mole percent. Express the mole percent to three significant figures.

Answer 1

A) Molarity = number of moles per litre of solution

Molecular weight of sucrose is 342 g

= (50.4/342)/(355/1000)

= 0.415 M

B) Molality =  (50.4/342)/0.332

= 0.444

C) Mass percent = (50.4/(332 + 50.4))*100 = 13.2 %

D) Number of moles of sucrose = (50.4/342) = 0.1474

Number of moles of waater = 332/18 = 18.4444

Thus mole fraction of sucrose =  0.1474/( 0.1474 + 18.4444 )

= 0.008

Mole fraction of water = 1 - 0.008 = 0.992

E) Mole percent of sucrose = mole fraction * 100 = 0.8 %

Mole percent of water = mole fraction * 100 = 99.2 %