Question

in a solution with density 1.5 gram per ml 150 gram of the solute is present in 750 gram of the solution the mass by volume percentage of the solution is

Answer 1

The molality is 0.50 mol/kg.

molality =
moles of [solute](http://socratic.org/chemistry/solutions-and-their-behavior/solute)
kilograms of [solvent](http://socratic.org/chemistry/solutions-and-their-behavior/solvent)

moles of NaOH = 10 g NaOH ×
1
mol NaOH
40.00
g NaOH
= 0.25 mol NaOH

kilograms of H₂O = 500 g H₂O ×
1
kg H₂O
1000
g H₂O
= 0.500 kg H₂O

molality =
moles of solute
kilograms of solvent
=
0.25
mol
0.500
kg
= 0.50 mol/kg