A vessel of 4.0 L capacity at S. T.P. contains a gaseous mixture of 8 g oxygen and 112cm3 of CO2 at S.T.P.  Calculate the pressure exerted by O2 and CO2 gases. Also calculate the total pressure exerted by the mixed gases.

No.of moles of O2 : nO2=8g32gmol−=0.25molP=?,V =4.0L, R=22.4273=0.0821LatmK−mol−;T=273K⋅  PO2=nRTVPO2=0.25mol×22.4×273K4.0L×273 =0.25×5.6=1.4atmFor CO2: no. of mol ofNo.of moles of CO2 : nCO2= volume of CO2 at NTP molar volume of CO2=112cm322400cm3=5×10−3molP=?;V=4.0L; R= 22.4273 =0.0821LatmK−mol−;T=273K;     PCO2=nRTV=5×10−3mol×22.4×273K4.0L×273=0.028atmTotal pressure =PO2+PCO2=1.4atm+0.028 atm=1.428atm≈1.43atm