1. 1 Partial Pressure Pressure of individual gases in a mixture

2. 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

3. 2 atm 1 atm 3 atm 6 atm

4. 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?

5. 5 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?

6. Ratio of the number of moles of a component in a mixture to the total number of moles in the mixture Numerically equal to the ratio of the partial pressure of a component gas to the total pressure of the gas mixture Mole Fraction

7. The partial pressure of oxygen was observed to be 156 torr in air with a total atmospheric pressure of 743 torr. Calculate the mole fraction of oxygen in the sample. Example

8. Gas Collection 8

9. 9 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

10. Water Vapor Pressure 10 Pressure of the water vapor depends on the temperature at which the gas is collected

11. Example 11 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?