10.7 – NOTES Ideal Gas Laws

IV. The Ideal Gas Law describes behavior of an ideal gas in terms of P, V, T, and n

A. Real versus ideal gases * particles have volume *subject to intermolecular forces *actual experimental measurements show behavior *closely resembles ideal behavior Ideal: * particles take up no space *no intermolecular/attractive forces * follows the gas laws under ALL conditions of T & P

At what conditions do the gas laws NOT work well? Extremely high pressures and low temperatures  close to condensation point   Polar gas molecules (H2O due to increased intermolecular forces) Very large molecules (butane due to larger actual volume than smaller particles)

B. Ideal Gas Law PV = nRT Describes the physical behavior of an ideal gas in terms of P, V, T, and # moles present (n); R = ideal gas constant – an experimentally determined constant whose value in the ideal gas equation depends on the units that are used for pressure – 0.0821 L•atm/mol•K

Example: 1. Calculate the number of moles if a gas occupies a volume of 3.0L at 1.50 atm and 300. K. PV = nRT n = PV/RT n = PV = (1.50)(3.0) n = 0.18mol RT (0.0821)(300)  

2. Determine the temperature (°C), given 2. 49 moles of a gas in a 1 2. Determine the temperature (°C), given 2.49 moles of a gas in a 1.00 L vessel at a pressure of 1073 torr. PV = nRT 1073 torr x ______1 atm______ = 1.41 atm 760 torr T = PV = (1.41)(1.00) T = 7 K = -266°C nR (0.0821)(2.49)  

3. Find the volume of 0.323moles of a gas at 265K and 0.900atm. PV = nRT V = nRT = (0.323)(0.0821)(265) V =7.81 L P (0.900)