Question

Mole fraction of C₃H₅(OH)₃ in a solution of 36 g of water and 46 g of glycerine is ______.

Options

• 0.46

• 0.36

• 0.20

• 0.40

Answer 1

Mole fraction of C₃H₅(OH)₃ in a solution of 36 g of water and 46 g of glycerine is 0.20.

Explanation:

Molar mass of glycerine C₃H₅(OH)₃ = 3 × 12 + 8 × 1 + 3 × 16

= 92 g/mol

Molar mass of water (H₂O) = 1 × 2 + 16

= 18 g/mol

Number of moles = `"mass"/"molecular weight"`

Number of moles for glycerine = `46/92`

= 0.5 moles

Number of moles for water = `36/18`

= 2 moles

Total number of moles = 0.5 + 2

= 2.5 moles

Mole fraction of glycerine = `"Number of moles of glycerin"/"Total number of moles"`

= `0.5/2.5`

= 0.20

∴ The mole fraction of glycerine is 0.20.