1. COMBINED AND IDEAL GAS LAWS

2. COMBINED GAS LAW  Do variables remain constant for gases???  Temperature, pressure, and volume are CONSTANTLY changing for a gas based on the conditions  Gas amount (n) is constant

3. COMBINED GAS LAW (CONT.)  Combination of all three laws into one equation (Boyle’s, Charle’s, and Gay-Lussac’s Laws)  Describes the relationship between pressure, volume, and temperature  Focus on initial and final conditions

4. COMBINED GAS LAW P 1 V 1 = P 2 V 2 T 1 T 2  Temperature—Kelvin

5. EXAMPLE 1: A gas has a volume of 80.0ml at 27°C and 0.200 atm. What volume will the gas have at standard conditions?

6. EXAMPLE 2: A gas has a volume of 60.0ml at standard conditions. This volume is reduced to 10.0ml at 25.0°C. What is the necessary pressure for this volume reduction?

7. IDEAL GAS LAW Describes the general relationship among the variables: Temperature Pressure Volume Number of moles of gas Enables us to determine the value of a variable if the other three variables are known

8. IDEAL GAS LAW (CONT.) PV = nRT P = pressure (atmospheres) V = volume (liters) T = temperature (Kelvin) n = moles of the gas R = 0.08206 L  atm/mol  K ( ideal gas constant )

9. EXAMPLE 1: Many gases are available for use in the laboratory among compressed gas cylinders stored at high pressures. Calculate the mass of O 2 (in grams) that could be stored at 21°C and 170atm in a cylinder with a volume of 60.0L.

10. EXAMPLE 2: Calculate the molecular weight of butane if 0.5813g of the gas fills a 250.0ml flask at a temperature of 24.4°C and a pressure of 742.6 mmHg.

11. EXAMPLE 3: Calculate the density in grams per liter of O 2 gas at 0°C and 1.00 atm.

12. EXAMPLE 4: A tank of hydrogen gas has a volume of 22.9L and holds 14.0 mol of gas at 12°C. What is the reading on the pressure gauge in atmospheres?

13. HOMEWORK Finish Gas Study Chart