Answer:
0.07mol/kg
Explanation:
Given parameters:
Mass of NaCl solution = 120g
Mass of water = 30kg
Unknown:
Molality of the solution =?
Solution:
The molality of a solution is the number of moles of the solute per mass of the solution.
Molality = [tex]\frac{number of moles of solute}{mass of solution}[/tex]
Number of moles of NaCl = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of moles of NaCl = [tex]\frac{120}{58.5}[/tex] = 2.05mole
So;
molality = [tex]\frac{2.05}{30}[/tex] = 0.07mol/kg
