1. Chapter 18 Dalton’s Law of Partial Pressures

2. We all live in the ocean of air, called the atmosphere.

3. Teacher Demonstration The syringe demo

4. Barometers and Standard Atmospheric Pressure

5. Standard atmospheric pressure defined as the pressure sufficient to support a mercury column of 760mm high. (units of mmHg, or torr). Another unit was introduced to simplify things, the atmosphere (1 atm = 760 mmHg). 1 atm = 760 mmHg = 760 torr = 101.3 kPa.

6. STP standard temperature and pressure Standard temperature 0°C or 273 K Standard pressure 1 atm (or equivalent)

7. Dalton’s Law of Partial Pressure The total pressure of a mixture of gases is the sum of the partial pressures of all the gases in the container. The contribution each gas makes to the total pressure of a mixture of gases is known as the partial pressure of that gas. P total = P A + P B + P C P total = 100 kPa + 250 kPa + 200 kPa = 550 kPa A 550 kPa

8. Turn to the “Dalton’s Law of Partial Pressures” sheet in your notebook.

9. Air is composed primarily of four gases: nitrogen (593.4 torr), argon (7.098 torr), carbon dioxide (0.2508 torr), and oxygen. What is the partial pressure of oxygen at standard atmospheric pressure? 593.4 torr + 7.098 torr + 0.2508 torr = 600.7488 torr ≈ 600.7 torr 760 torr – 600.7 torr = 159.3 torr ≈ 159 torr

10. Air is composed primarily of four gases: nitrogen (593.4 torr), argon (7.098 torr), carbon dioxide (0.2508 torr), and oxygen. What percent of air is nitrogen? 593.4 torr 760 torr x 100 = 78.1%

11. Air is composed primarily of four gases: nitrogen (593.4 torr), argon (7.098 torr), carbon dioxide (0.2508 torr), and oxygen. What is the partial pressure in kPa of argon gas at standard atmospheric pressure? 7.098 torr

12. Air is composed primarily of four gases: nitrogen (593.4 torr), argon (7.098 torr), carbon dioxide (0.2508 torr), and oxygen. What is the partial pressure in kPa of argon gas at standard atmospheric pressure? 7.098 torr 760 torr 101.3 kPa = 0.946 kPa

13. What would be the partial pressure of oxygen on top of a high mountain where the air pressure is only 534 mm Hg? 159 torr 760 torr = X 534 torr x = 112 torr Remember from the first problem that the partial pressure of oxygen in air is 159 torr

14. What percent less oxygen is dissolved into the blood on top of the mountain as compared to sea level? 112 torr 159 torr x 100= 70.4% 100 – 70.4 = 29.6% less

15. Mount Everest

16. Endurance Training

17. Homework  Dalton’s Law of Partial Pressures and Ideal Gases Worksheet