1. Solution Concentration

2. Calculations of Solution Concentration: Mass Percent
Mass percent is the ratio of mass units of solute to mass units of solution, expressed as a percent

3. A Simplifying Assumption
1 ml of water = 1 gram of water
1000 ml of water = 1 liter = 1000 grams
Assume that solutions with water as the solvent have the density of pure water (1 mL = 1 gram)
It’s not true, but it’s close enough 

4. Calculations of Solution Concentration
Mole fraction – the ratio of moles of solute to total moles of solution

5. Calculations of Solution Concentration: Molarity
Molarity is the ratio of moles of solute to liters of solution

6. Preparation of Molar Solutions
Problem: How many grams of sodium chloride are needed to prepare 1.50 liters of M NaCl solution?
Step #1: Ask “How Much?” (What volume to prepare?)
Step #2: Ask “How Strong?” (What molarity?)
Step #3: Ask “What does it weigh?” (Molar mass is?)
1.500 L
0.500 mol
58.44 g
= 43.8 g
1 L
1 mol

7. Calculations of Solution Concentration
Molality – moles of solute per kilogram of solvent

8. Serial Dilution
Problem: What volume of stock (11.6 M) hydrochloric acid is needed to prepare 250. mL of 3.0 M HCl solution?
MstockVstock = MdiluteVdilute
(11.6 M)(x Liters) = (3.0 M)(0.250 Liters)
x Liters = (3.0 M)(0.250 Liters)
11.6 M
= L