The Ideal Gas Law

Remember… and In an Ideal Gas, Therefore, in an Ideal Gas, Combined Gas LawAvogadro

The Universal Gas Constant Since all gases behave in a similar way, the Universal Gas Constant (R), can be derived from the equation above.

The Ideal Gas Law Where

Guidelines for using the Ideal Gas Law Always convert the temperature to kelvins (K) Always convert the masses to moles (mol). Always convert the volumes to litres (L). Convert the pressures to kilopascals (kPa).

Sample problems How many moles of H 2 is in a 3.1 L sample of H 2 measured at 300 kPa and 20°C? PV = nRT (300 kPa)(3.1 L) = n (8.31 kPa L/K mol)(293 K) (8.31 kPa L/K mol)(293 K) (300 kPa)(3.1 L) = n = 0.38 mol How many grams of O 2 are in a 315 mL container that has a pressure of 12 atm at 25°C? P = 300 kPa, V = 3.1 L, T = 293 K PV = nRT (8.31 kPa L/K mol)(298 K) ( kPa)(0.315 L) = n = mol P= kPa, V= L, T= 298 K mol x 32 g/mol = 4.95 g

Finding Molar Mass A scientist isolates 2.366g of a gas. The sample occupies a volume of 800mL at 78.0  C and 103kPa. Calculate the mass of the gas. Is the gas mostly likely to be bromine, krypton, neon or fluorine? Therefore, the gas is Krypton