Question

Calculate mole fraction ,molarity,molality of solution containing 20% by mass of ch3cooh in water if dencity of solution is 1.026g/ml

Answer 1

Explanation:

40% ethylene glycol means

mass of ethylene glycol =

40 g

mass of water (solvent) =

60 g = 0.060 kg

mass of solution =

100 g

1. Molality

Molar mass of ethylene glycol =

62.07 g/mL

no. of moles =

4 g

62.07 g.mol

−

1

=

0.6444 mol

Molality =

no. of moles

mass of solvent in kg

Molality =

0.6444 mol

0.060 kg

=

10.7 m

2. Molarity

Molarity

=

no. of moles

volume of solution in litres

Density

=

1.05 g/cm

3

Volume

=

Mass

Density

Volume

=

100 g

1.05 g/mL

=

95.24 mL

=

0.0952 L

Molarity

=

0.6444 mol

0.0952 L

=

6.76 M or 6.76 mol/L

3. Mole fraction

no. of moles of water

=

60 g

18.02 g.mol

-1

=

3.329 mol

Total moles

=

(3.329 + 0.6444) mol

=

3.974 mol

mole fraction of ethylene glycol

=

0.6444

3.974

=

0.162