If 4 g of NaOH dissolves in 36 g of H2O, calculate the mole fraction of each component in the solution. Also, determine the molarity of the solution (specific gravity of solution is 1g mL–1).
If 4 g of NaOH dissolves in 36 g of H2O, calculate the mole fraction of each component in the solution. Also, determine the molarity of the solution (specific gravity of solution is 1g mL–1).

Calculation:

Mole fraction of H2O = Number of moles of H2O / Total number of moles (H2O +NaOH)

1. Number of moles of H2O = 36/18

Number of moles of H2O =2 moles

1. Number of moles of NaOH = 4/40

Number of moles of NaOH =0.1 mol

1. Total number of moles = 2 + 0.1

Total number of moles = 2.1

1. Mole fraction of H2O = 2/2.1

Mole fraction of H2O = 0.952

1. Mole fraction of NaOH = 0.1/2.1

Mole fraction of NaOH = 0.048

1. Mass of solution = Mass of H2O + Mass of NaOH

Mass of solution = 36+4

Mass of solution = 40g

1. Volume of the solution = 40/1

Volume of the solution = 40mL

1. Molarity of the solution = 0.1/0.04

Molarity of the solution = 2.5M