Question

Commercially prepared concentrated HCl is an aqueous solution that is 37.1% by mass HCl and has a density of 1.18 g/mL. (Water is the solvent). Determine the molarity and molality of HCl in this solution.

Answer 1

1) to Determine moles of HCl in 100.0 g of 37.7% solution: molar mass of hcl =  36.4609 g/mol

37.7 g of this solution is HCl

no of moles = given mass/ molar mass

37.7 g / 36.4609 g/mol = 1.03398435 mol present

2) to Determine volume of 100.0 g of solution: as 37.1 % means 37.1g dissolved in 100 g of water

density = mass / volume

1.19 g/mL = 100.0 g / x

x = 84.0336 mL

3) Determine molarity = no of moles of solute dissolve per litre of solution

1.03398435 mol / 0.0840336 L = 12.3 M

4) molarity =  no of moles of solute dissolve per kg of solvent mass of water 100- 37.1

1.03398435 mol *1000/ 62.9 = `16.44 m