Question

16. If a sample of oxygen gas is collected over water at a pressure of 0.921 atm and 23°C, whatis the partial pressure of the oxygen gas?

17. A mixture of gases exerting a pressure of 1.11 atm consists of 0.20 mol of O2 gas, 0.3 mol of H2 gas, and 0.7 mol of CO2 gas. What is the partial pressure of the O2

gas, the H2 gas andthe CO2 gas?

18. 0.5 mol of O2 is added to a cylinder containing 0.7 mol of H2 at 0.6 atm. What is the molefraction of each gas? What is the partial pressure of O2

and the total pressure of thecylinder?

Answer 1

16. vapor pressure of water at 23C⁰   = 0.02773 atm

   partial pressure of O2 = atmosphric pressure - vapor pressure of water

                                        = 0.921-0.02773 = 0.89327 atm

17. total pressure of gases mixture   = 1.11atm

    no of moles of O2 nO2 = 0.2 moles

   no of moles of H2 nH2   = 0.3 moles

   no of moles of Co2 nCO2 = 0.7 moles

Total no of moles of gases mixture n = 0.2 + 0.3 + 0.7 = 1.2 moles

mole fraction of O2 = nO2/nO2+nH2 + nCo2

                                   = 0.2/1.2 = 0.166

mole fraction of H2 XH2 = nH2/nO2+nH2 + nCo2

                                 = 0.3/1.2 =0.25

mole fraction of CO2 XCo2 = nCO2/nO2+nH2 + nCo2

                                              = 0.7/1.2   = 0.583

partial pressure of O2 PO2 = XO2 * PT

                                               = 0.166*1.11 = 0.1843atm

partial pressure of H2 PH2 = XH2 * PT

                                              = 0.25*1.11 = 0.2775atm

partial pressure of CO2 PCO2 = XCO2 * PT

                                                    = 0.583*1.11 = 0.647atm