Question

A)What is the total vapor pressure in atm of a solution created by combining 4.43 moles of toluene and 5.38 moles of benzene at 350K? At 350K P_{vap, toluene} = 0.33 atm and P_{vap, benzene} = 0.95 atm

B)What is the molar mass of a non-ionizing, non-volatile solid that when 10.4 g is dissolved in water to make 100.0 mL of solution creats a solution with an osmotic pressure of 6.07 atm at 25.0^oC

C)What is the freezing point of an aqueous solution made by dissolving 0.151 mole of MgCl₂ in 100.0 g of water? K_f = 1.86 ^oC/m

Answer 1

V = mass X R X T /molar mass

molar mass = mass X R X T / V

                   = 10.4 X 0.0821 X 298/ 6.07 X 0.1

                   = 419.18 g/mol.

Tf = Kf X molality

molality = mass/molar mass X 1000/ mass of solvent in grams

               = (0.151) X (1000/100)

               = 1.51

Tf = 1.86 X 1.51

         = 2.8086

Tf = T0-T1 ( T0 = freezing point of solvent, T1 = freezing point of solution)

T1 = Tf - T0

     = 2.8086 - 0.0

     = 2.8086⁰C