TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. The ideal gas law The ideal gas law: the gas law that includes all four variables: P, V, T, and n When the pressure, volume, and temperature of a contained gas are known, you can use the ideal gas law to calculate the number of moles of the gas.

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Pressure (P) The (P) in PV = nRT Force exerted over an area Measured in: Millimeters of mercury (mm Hg) Kilopascals (kPa) Atmospheres (atm) 1 atm = 760 mmHg = kPa

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Practice 1. The pressure of a tire is measured as 29.4 kPa. What is this pressure in mmHg? 2. What is 475 mmHg expressed in atm?

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Volume The (V) in PV = nRT How much space something takes up Measured in liters (L) 1 L = 1000 ml = 1000 cm 3

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Moles The (n) in PV = nRT The number of gas particles Measured in moles (mol) 1 mol occupies 22.4 L

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Temperature The (T) in PV = nRT The average kinetic energy of the gas particles (temperature) Measured in Kelvin (K) Kelvin = ( o C) ( o C) = (5/9) x ( o F – 32) = K - 273

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Practice 3. What is 450 K in degrees Celsius? 4. What is 27 degrees Fahrenheit in Kelvin?

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law.

Gas Constant The (R) in PV = nRT Is a universal constant required to make the Ideal Gas Law work. Its value depends on what pressure units you are using: If using atm; R = (L)(atm)/(mol)(K) If using kPa; R = 8.31 (L)(kPa)/(mol)(K) If using mmHg; R = 62.4 (L)(mmHg)/(mol)(K)

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Standard Temperature and Pressure (STP) The volume of a gas varies with a change in temperature or a change in pressure. Due to these variations, the volume of a gas is usually measured at a standard temperature and pressure. Standard temperature and pressure (STP) means a temperature of 273 K and a pressure of kPa/1 atm/760 mmHg. At STP, 1 mol (6.02  representative particles) of any gas occupies a volume of 22.4 L. The quantity 22.4 L is called the molar volume of a gas. (contd.)

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Practice 5. Assuming ideal gas behavior, calculate the number of moles of oxygen, as described by the ideal gas law, in a 12.5-L tank if the pressure is 25,325 kPa and the temperature is 22ºC. 6. At 34ºC, the pressure inside a nitrogen-filled tennis ball with a volume of L is 212 kPa. How many moles of nitrogen gas are in the tennis ball? (contd.)

TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law, Charles’ law, Avogadro’s law, Dalton’s law of partial pressure, and the ideal gas law. Practice 7. What is the volume of 2.30 moles of hydrogen gas at a pressure of 122 kPa and temperature of 20.0 o C? 8. How much N 2 is required to fill a small room with a volume of 27,000 L to 0.98atm at 25 o C?