1. Solubility & Concentration
CREDIT: D. Scott, CHS

2. Concentration of Solution
Solvent Solute

3. Concentration of Solution
Molarity
Parts ratio
Mole Fraction
Moles of solute
Liter of solution
Mol L
(M) = =
amount of solute (g or ml)
amount of solution (g or ml) =
(102) or (106) or (109)
(c)
Moles of solute
Total moles of solution =

4. Molarity Example Problem 1
NaCl
12.6 g of NaCl are dissolved in water making 344mL of solution. Calculate the molar concentration.

5. Molarity Example Problem 2
NaCl
How many moles of NaCl are contained in 250.mL of solution with a concentration of 1.25 M?
Volume x concentration = moles solute

6. Molarity Example Problem 3
NaCl
What volume of solution will contain 15 g of NaCl if the solution concentration is 0.75 M?
moles solute ÷ concentration = volume solution

7. Mass and volume units must match.
% Concentration
% (w/w) =
% (w/v) =
% (v/v) =
Mass and volume units must match.
(g & mL) or (Kg & L)

8. % Concentration Example Problem 1 Example Problem 2
(Solid in a Liquid)
What is the concentration in %w/v of a solution containing 39.2 g of potassium nitrate in 177 mL of solution?
% (w/v) =
Example Problem 2
(Liquid in a Liquid)
What is the concentration in %v/v of a solution containing 3.2 L of ethanol in 6.5 L of solution?
% (v/v) =

9. What volume of 1.85 %w/v solution is needed to
% Concentration
Example Problem 3
What volume of 1.85 %w/v solution is needed to
provide 5.7 g of solute?
% (w/v) =
We know:
We want to get:
g solute ÷ concentration = volume solution

10. Parts per million/billion (ppm & ppb)or
= ppm or
= ppb
AND
For very low concentrations:
= ppt
parts per trillion
Mass and volume units must match.
(g & mL) or (Kg & L)

11. ppm & ppb or Example Problem 1
An Olympic sized swimming pool contains 2,500,000 L of water. If 1 tsp of salt (NaCl) is dissolved in the pool, what is the concentration in ppm?
1 teaspoon = 6.75 g NaCl or

12. ppm & ppb or Example Problem 2
An Olympic sized swimming pool contains 2,500,000 L of water. If 1 tsp of salt (NaCl) is dissolved in the pool, what is the concentration in ppb?
1 teaspoon = 6.75 g NaCl or

13. Mole Fraction c A = c B = Mole Fraction (c) moles of A
sum of moles of all components A B +
c B =
moles of B
sum of moles of all components B A +
Since A + B make up the entire mixture, their mole fractions will add up to one.

14. Mole Fraction Example Problem 1
In our glass of iced tea, we have added 3 tbsp of sugar (C12H22O11). The volume of the tea (water) is 325 mL. What is the mole fraction of the sugar in the tea solution?
(1 tbsp sugar ≈ 25 g)
First, we find the moles of both the solute and the solvent.
Next, we substitute the moles of both into the mole fraction equation.

15. Mole Fraction Example Problem 2
Air is about 78% N2, 21% O2, and 0.90% Ar.
What is the mole fraction of each gas?
First, we find the moles of each gas. We assume 100. grams total and change each % into grams.
Next, we substitute the moles of each into the mole fraction equation.