Answer: 1.86 m
Explanation:
Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.
[tex]Molality=\frac{n\times 1000}{W_s}[/tex]
where,
n = moles of solute
[tex]W_s[/tex] = weight of solvent in g
Given : 15.0 grams of [tex]MgCl_2[/tex] is present in 100 g of solution
Moles of solute [tex]H_2O=\frac{\text {given mass}}{\text {Molar mass}}=\frac{15.0g}{95.3g/mol}=0.16[/tex]
mass of solution = 100 g
density of solution = 1.127g/ml
mass of solvent = mass of solution - mass of solute = 100 g - 15.0g = 85.0 g
[tex]Molality=\frac{0.16\times 1000}{85.0g}=1.86[/tex]
Thus molality of a 15.0% by mass solution of [tex]MgCl_2[/tex] is 1.86m.
