Question

1.How much water would be needed to completely dissolve 1.79 L of the gas at a pressure of 720 torrand a temperature of 21 ∘C? A gas has a Henry's law constant of 0.183 M/atm .

2.To what volume should you dilute 40.0 mL of a 4.45 M KI solution so that 23.5 mL of the diluted solution contains 3.15 g of KI?

3. The solvent for an organic reaction is prepared by mixing 70.0 mL of acetone (C3H6O) with 49.0 mLof ethyl acetate (C4H8O2). This mixture is stored at 25.0 ∘C. The vapor pressure and the densities for the two pure components at 25.0 ∘C are given in the following table. What is the vapor pressure of the stored mixture?

Compound	Vapor pressure (mmHg)	Density (g/mL)
acetone	230.0	0.791
ethyl acetate	95.38	0.900

Answer 1

1.)

Pressure = 720 torr = 720 /760 = 0.947 atm

Henry's law constant = K = 0.183 M/atm

molarity of water = K x P

                           = 0.183 x 0.947

                            = 0.1733 M

molarity = moles / volume

0.1733 = moles / 1.79

moles = 0.1733 x 1.79 = 0.31

moles = weight / molar mass

0.31 = weight / 18

weight of water = 5.58 g --------------------------> answer

2.)

molarity = (3.15 / 166 ) x 1000 / 23.5

              = 0.8075 M

M1 V1 = M2 V2

M1 = 4.45 , V1 = 40 ml , M2 = 0.807 M , V2 = ?

4.45 x 40 = 0.8075 x V2

V2 = 220.4 ml

diluted volume = 220.4ml --------------------------> answer

3)

acetone mass = density x volume = 0.791 x 70 = 55.37 g

acetone molar mass = 58 g/mol

acetone moles = 55.37 /58 = 0.955

ethyl acetate mass = 0.900 x 49 = 44.1 g

ethyl acetate molar mass =88 g /mol

ethyl acetate moles = 44.1 /88 = 0.501

total moles = 0.955 + 0.501 = 1.002

mole fraction of acetone = 0.501 / 1.002 = 0.499

mole fraction of ethyl acetate = 1 - 0.499 = 0.5001

Pacetone = mole fraction x pure state pressure

                 = 0.499 x 230

                 = 114.77 torr

P ethyl acetate = 0.501 x 95.38

                         = 47.78

total pressure = 114.77 + 47.78

                      = 162.55 torr