Gas Laws Summary Table Definitions: P = pressure n = # of moles V = volume R = gas constant (0.0821 L•atm/mol•K); this is the most common one T = temperature (in Kelvin always for gas laws!) molar volume: 1 mol/22.4 L or 22.4L/1 mol of any gas at STP STP: standard temperature = 00C or 273 K K = 0C + 273 standard pressure = 1 atm = 760 mm Hg = 760 torr = 101.3 kPa M = Molar Mass (on Ref. Tables packet M is molarity – it is italicized!!) Name Formula Special Conditions; Special Notes Regarding Some Examples of Other information Units Key Words in or missing from word Problems Combined Gas Law P1V1 = P2V2 n is constant T always in K no mass or moles given T1 T2
Boyle’s Law P1V1 = P2V2 n and T are constant consistent units for T is constant or not PV = k inverse relationship pressure and volume mentioned; no mass or P↑V↓ and P↓V↑ moles given
Charles’ Law V1 = V2 n and P are constant T always in K P is constant or not direct relationship V1/T1 = k T1 T2 consistent units for V mentioned; no mass or V↑T↑ and V↓T↓ moles given
Gay-Lussac’s Law P1 = P2 n and V are constant T always in K V is constant or not direct relationship P1/T1 = k T1 T2 consistent units for P mentioned; no mass or P↑T↑ and P↓T↓ moles given
Dalton’s Law of Partial Pressures PT = P1 + P2 + P3 +… sum of partial pressures consistent units for P partial pressure – sum of all gases in a fixed of them or find one of container them given PT
Special Case of Dalton’s Law Patm = Pg + PH2O use for collection of a consistent units for P pressure of a dry gas gas over water collected over water Graham’s Law of Effusion rate of gas A = √M of gas B M is the molar mass NO Units – this is a ratio ratio of speed, effusion, rate of gas B √M of gas A (from periodic table) or comparison diffusion; comparison of (notice diatomics!) 2 gases Ideal Gas Law PV = nRT only R is constant units used must be moles or mass is given must use R value consistent with R; or to be found in the consistent with usually P in atm; V in L; problem pressure units T always in K! Gas Density at STP D = Molar Mass can only use at STP usually in g/L for gases find density or molar Molar Volume (standard conditions) mass when given density at STP Gas Density NOT at STP D = PM must use when usually in g/L for gases find gas density or RT conditions are not at molar mass when given STP density **Highlighted Info Given in NCDPI Reference Tables**