Question

4. a) Define Gay-Lussac's law. b) In equation form, Gay-Lussae's law is 5. A Chem 1314 student determines the mass of an unknown gas to be 0.99 grams at 43 °C and 745 mm Hg in a 200 mL container. What is the molecular mass of the unknown gas? [show work] The "unknown" gas (among the following) is most probably a) propane, CH. b) sulfur hexafluoride, SF6c) Xenon, Xe d) pentane, CHia CHEM1314-YEAR 2019-2020

Answer 1

4) a) According to Gay-lussac's law, at constant volume, the pressure of the gas is directly proportional to its absolute temperature Absolute temperature means "C +273 temperature in kelvins = b) Pressure is directly proportional to its absolute temperature. P KT then i.e. P o T therefore P/T (K) constant, for two gases P/TI PT2 T1 T2

weight= o 449 the data mass F Yom Temperature (T) 432 43+273 T 316K we know that = latm 14tm x 745mm o.98 atm 76owwg Volume = 000 M 1L A L o aL 00oM hat ideal 4as equaton PV- nRT we Know weight P V PV RT RT moky mass R = Substitute all the Valves in Kmol weight) RT MolaTmass Pv (6.44 (.082 atm mol h316 Molax mass 131 mel (0.48 at (oa : Moly mass of umhhow gas = 172 9/mo

Su 9/mol la(3)+ 8() = 32 6(14) 463/mol S 13L 7a /mol mnown gas An Suwex. C