Question

What is the mole fraction of water in a solution that is 37.9% by weight ethylene glycol? The chemical formula of ethylene glycolis HOCH CH2OH. OOO Select one: O a. 5.63 O b. 0.849 o c.0.177 O d. 0.901 O e. 0.379

Answer 1

Consider 100 g of solution

Then mass of HOCH2CH2OH = 37.9 g

Mass of H2O = 100 g - 37.9 g

= 62.1 g

Molar mass of H2O,

MM = 2*MM(H) + 1*MM(O)

= 2*1.008 + 1*16.0

= 18.016 g/mol

mass(H2O)= 62.1 g

use:

number of mol of H2O,

n = mass of H2O/molar mass of H2O

=(62.1 g)/(18.02 g/mol)

= 3.447 mol

Molar mass of C2H6O2,

MM = 2*MM(C) + 6*MM(H) + 2*MM(O)

= 2*12.01 + 6*1.008 + 2*16.0

= 62.068 g/mol

mass(C2H6O2)= 37.9 g

use:

number of mol of C2H6O2,

n = mass of C2H6O2/molar mass of C2H6O2

=(37.9 g)/(62.07 g/mol)

= 0.6106 mol

Mole fraction of H2O = mol of H2O / total mol

= 3.447 / (3.447 + 0.6106)

= 0.849

Answer: 0.849