What is the molality of a 30.0% by mass hydrochloric acid solution ? The density of the solution is 1.0980g/mol.

Answer 1

molality = moles HCl/Kg Solvent

Given 30% Soln by mass = 30gHCl/100gSoln

Moles HCl = (30g/36g/mol) = 0.833mole
Kg Solvent = (100gSoln/1.098g/ml) = 91.1ml = 91.1gms Soln(1.10g/ml 30%HClsoln*)= 100.21gms of 30%HCLSoln = 0.1002Kg Soln = 60%(0.1002Kg) = 0.60(0.1002)Kg Solvent = 0.0601Kg Solvent

*specific gravity of 30%HCl aqueous soln = 1.10 = 1.10g/ml if solvent is HOH.

molality = (0.833moleHCl)/(0.0601KgSolvent)
=13.85 molal HCl soln