1. 8.2 Measuring Concentration Objective 2
Chemistry

2. Essential Questions What are ppm and ppb and what are they used for?
How do you calculate molarity?
How do you calculate molality?

3. Measurement of Concentration (don’t need to write down)
There are many ways to indicate concentration
Molarity
Molality
Mole fraction
Weight/volume percent
Volume/volume percent
Parts per million and parts per billion
Different fields of sciences use different ways

4. “Parts Per” Used to measure very, very small concentrations
Usually used for trace elements in the earth or toxins present in the environment
Parts Per million (ppm) – one out of every one million parts
Others are ppb, and ppt

5. Molarity (M) Most useful in chemistry for liquid solutions
Note: 1 L = 1000 mL

6. Molarity (cont) Find molarity for the following:
4.4 mol NaCl in 13 L H2O
.36 mol Br2 in 83 mL H2O
52 g KOH in 601 mL
65 g Al(OH)3 in 253 mL

7. Molality (m) Useful for solid solutions Formula:
Note: 1.0 kg H2O = 1.0 L H2O
1kg = 1000 g

8. Molality (cont) Find the molality for 6.3 mol KCl in 8.00 kg water
Find molality for 16.1g Cl2 in 5000g of water
Find the molality for 88 g NaOH in 520 g water
Find the molality of 4.32 g Rb3PO4 in 0.65 L H2O

9. Essential Questions What are ppm and ppb and what are they used for?
How do you calculate molarity?
How do you calculate molality?

10. 8.2 Tracked Assignment
worksheet