Question

15.434 g of kcl (m.m 74.55 g/mol) is dissolved in water up t a total volume of 500.0 mL. the density of this solution is 1.02 g/mL. what is the concentration of he solution in molality

Answer 1

Answer:

0.412mol/Kg

Explanation:

First, let us fine the number of mole of KCl.. This is illustrated below

Mass of KCl = 15.434g

Molar Mass of KCl = 74.55 g/mol

Number of mole = Mass /Molar Mass

Number of mole KCl = 15.434/74.55 = 0.21mole

Now, let us calculate the mass of the water in kg. This can be achieved by doing the following:

Density = 1.02 g/mL

Volume = 500mL

Mass =?

Mass = Density x volume

Mass of water = 1.02 x 500 = 510g

Converting 510g to kg, we have: 510/1000 = 0.51kg

Now we calculate for the molality as follows:

Mole of the solute = 0.21mole

Mass of the solvent = 0.51Kg

Molality = mole of solute /mass of solvent

Molality = 0.21/0.51

Molality = 0.412mol/Kg