Concentrations of Solutions

What are the components of a Solution?

Solute and Solvent

Do the components in a solution have differences?

Concentration of SolutionsRefers to amount of solute dissolved in a unit amount of solvent or of solution.

Expressed in:- Percent Composition (by mass or volume)- Molarity- Molality- Mole Fraction

Percent CompositionPercent by Mass

% by mass = Mass of solute X 100 Mass of solution

Percent by Volume% by volume = Volume of solute X 100

Volume of solution

Where: Mass/Vol. of sol’n = mass/vol. of solute + mass/vol. of solvent

1. What is the mass percentage of a solution made by dissolving 4.0 g NaCl in 100.0 g of water?

% by Mass = Mass of solute X 100 Mass of solution

= 4.0 g NaCl X 100100.0 + 4.0g

= 0.03846 X 100

= 3.846 %

2. A medical solution used is 0.9 % by mass of NaCl. How many grams of NaCl are present in 100.0 g of the solution?

% by Mass = Mass of solute X 100 Mass of solution

0.9 = (?) g NaCl X 100100.0 g of solution

= 0.9 g of NaCl

3. Dimercaprol, a compound used as an antidote for mercury and arsenic poisoning, is prepared by

mixing 100.0 mg of dimercaprol with 700.0 mg of peanut oil. What is the percent by mass of

dimecaprol in this solution? % by Mass = Mass of solute X 100

Mass of solution

= 100mg Dimercaprol X 100100.0mg Dimeracprol + 700.00mg peanut oil

= 100mg X 100800mg Solution

% = 12.5

4. What is the mass percent of NaCl in a solution that is made by dissolving 12.0 g of NaCl in 60.0 g of

H2O?% by Mass = Mass of solute X 100

Mass of solution

= 12.0 g NaCl X 10012.0g NaCl + 60.0 g H2O

= 12.0 g NaCl X 10072.0 g Solution

% = 0.166 X 100% = 16.6

5. What is the volume of alcohol in 500 mL of wine which contains 12% alcohol by volume? What is its

proof number?% by Mass = Volume of solute X 100

Vol. of solute + Vol. of solvent

12 = (?) volume of alcohol X 100 500.0 mL wine

12 = (?) volume of alcohol X 100 500.0 mL wine

6000mL = [(?) volume of alcohol] 100 100 100

60mL = volume of alcohol

6. A bottle of Lambanog is 80 proof. What is the percent by volume of alcohol in this bottle of

Lambanog?

Degree proof is twice the percent by volume.

Therefore: an 80 proof alcohol contains 40% by volume of alcohol

Thus: in every 100mL has 40mL of alcohol and 60mL water

Seatwork

1. What is the mass percent of mothball in a solution that is made by dissolving 12g of mothball

in 60.0 g of CCl4?

2. What is the percent volume of CCl4 in a solution that is made by dissolving 12ml of CCl4 in 1.0L of

kerosene?

3. What is the volume of CCl4 in a solution of 2.0L which contains 30% CCl4