What is Mass % of an aqueous NaOH solution in which molality of NaOH is 16.7m? Density of the solution is 1.4339g/ml

Answer 1

16.7 m means 16.7 mol NaOH/kg solvent.
16.7 mol NaOH = mols x molar mass = about 670 g but you need to this more accurately.
Thus 16.7 m contains about 670g NaOH/kg solvent. That is 670g/1000 g solvent.
The solution, then, must weigh 1000g + 670 g = 1670g.
mass% = (670/1670)*100 = ?
You don't need the density to calculate mass%.