Question

An aqueous solution is 8.00% ammonium chloride, NH4Cl, by mass. The density of the solution is 1.023 g/mL. What are the molality, mole fraction, and molarity of NH4Cl in the solution?

Answer 1

1)An aqueous solution is 8.00% ammonium chloride means that 8 gram is present in 100 g of solution

mass of soluvent = mass of solution - mass of solute = 100 - 8 = 92 g of water = 0.92 Kg

molaility = given mass / molar mass * 1/ mass of solvent in grams

= 8 / 53.5 * 1/ 0.92 = 0.1625 m ( molar mass of ammonium chloride = 53.5 g/mol)

2) mole fraction of ammonium chloride

8 g of ammonium chloride = 8/ 53.5 = 0.15 moles

92 g of water = 92 / 18 = 5.11 moles

mole fraction of ammonium chloride = 0.15 / 0.15 + 5.11= 0.03

3) 8 g of ammonium chloride = 0.15 moles

volume of solution = mass of solution /density of solution = 100/1.023 = 97.75 ml = 0.097L

molarity = no of moles of solute / volume of solution in liters = 0.15 moles /  0.097lit = 1.55 M