Question

A flask has a volume of 157.6 mL . When filled with air at a pressure of 839.8 torr and a temperature of 25.70 ∘C, the flask and air have a mass of 49.781 g . When filled with carbon dioxide at the same temperature and pressure, the mass of the flask and CO2 is 49.893 g. Part A - What is the mass of the carbon dioxide gas in the flask (when the flask is filled with carbon dioxide)?

Answer 1

Solution :-

Volume = 157.6 ml = 0.1576 L

Pressure = 839.8 torr * 1 atm / 760 torr = 1.105 atm

Temperature = 25.7 C + 273 = 298.7 K

Lets calculate the moles of the CO2 gas

PV= nRT

PV / RT = n

1.105 atm * 0.1576 L / 0.08206 L atm per mol K *298.7 K = n

0.007105 mol CO2 = n

Now lets convert moles of CO2 to its mass

Mass of CO2 = moles * molar mass

                        = 0.007105 mol * 44.01 g per mol

                        = 0.3127 g CO2

So the mass of the CO2 in the flask = 0.3127 g