Chemistry - Gold

Question

How many liters of oxygen collected over H2O and measured at 27.0 degrees Celsius and 745.0 mm Hg can be prepared by decomposing 4.421 g gold (I) oxide (a noble metal oxide)? The vapor pressure of H2O at 27.0 degrees Celsius is 26.7 mm Hg.

Answer 1

2Au2O ==> 4Au + O2

moles Au2O = 4.421 g x 1 mol/410 g = 0.01078 moles

moles O2 formed = 0.01078 mol Au2O x 1 mol O2/2 mol Au2O = 0.005391 moles O2

volume of O2 = nRT/P where n = 0.005391 moles; R = 0.0821 Latm/Kmol; T = 27+273 = 300K; P = 745 mm - 26.7 mm = 718.3 mm x 1 atm/760 mm = 0.9451 atm

V = (0.005391)(0.0821)(300)/(0.9451)

V = 0.1405 L