A solution was prepared by dissolving 31.0 g of KCl in 225 g of water. A.) Calcu

ID: 475251 • Letter: A

Question

A solution was prepared by dissolving 31.0 g of KCl in 225 g of water.

A.) Calculate the mass percent of KCl in the solution. Express your answer with the appropriate units.

B.) Calculate the mole fraction of the ionic species KCl in the solution. Express the concentration numerically as a mole fraction in decimal form.

C.) Calculate the molarity of KCl in the solution if the total volume of the solution is 239 mL. Express your answer with the appropriate units.

D.) Calculate the molality of KCl in the solution. Express your answer with the appropriate units.

Mass Percent of KCl = mass of KCl / (total mass of solution)

= {31.0 g / (31 + 225) } x 100

= 12.11 %

Lets find moles of KCl and H2O

Moles of KCl = 31.0 g /74.55 g/mol = 0.4158 moles

Moles of H2O = 225 g /18 g/mol = 12.5 moles

Then

Moles fraction of KCl = moles of KCl / total moles

= 0.4158 / (0.4158 + 12.5)

= 0.0322

Molarity of KCL = moles of KCl / Volume

= 0.4158 moles / 0.239 L

= 1.74 M

Molality of KCl = moles of KCl/ mass of solution

= 0.4158 moles / 0.239 Kg ..............................( density of water =1, so 0.239 L = 0.239 Kg)

= 1.74 m

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