1. 1

2. 2 Partial Pressure Pressure of individual gases in a mixture

3. Daltons’ Law of Partial Pressures The total pressure inside a container is equal to the partial pressure due to each gas. The partial pressure is the contribution by that gas. P Total = P 1 + P 2 + P 3 For example

4. We can find out the pressure in the fourth container. By adding up the pressure in the first 3. 2 atm 1 atm 3 atm 6 atm

5. Examples What is the total pressure in a balloon filled with air if the pressure of the oxygen is 170 mm Hg and the pressure of nitrogen is 620 mm Hg? In a second balloon the total pressure is 1.3 atm. What is the pressure of oxygen if the pressure of nitrogen is 720 mm Hg?

6. 6 More Examples What pressure is exerted by a mixture of 2.00 g of hydrogen gas and 8.00 g of nitrogen gas at 273 K and in a 10.0 L vessel? If a.20 L sample of oxygen at 0°C and 1 atm and a.10 L sample of nitrogen at 0°C and 2.0 atm are both placed in a.40 L container at 0°C, what is the total pressure of the mixture?

7. 7 Gas Collection When a gas is collected over water, water vapor ends up in the gas The pressure of the pure gas is the total pressure minus the pressure of the water vapor P tot = P gas + P water P gas = P tot - P water

8. 8 Water Vapor Pressure Pressure of the water vapor depends on the temperature at which the gas is collected

9. 9 Example Carbon dioxide gas is collected over water at a temperature of 18°C. The barometric pressure reads 775 mm Hg. What is the pressure of the carbon dioxide?