Choose O2 as the gas and set the following parameters: Pressure: 740 mmHg Mass: 200 mg Temperature: 35 °C What is the volume of O2 under these conditions, in liters?

Answer 1

Use the ideal gas law: PV = nRT where "P" is pressure, "V" is volume, "n" is the number of moles (which you must calculate), "R" is the ideal gas constant which is available in many different units but for this problem we can use R = 62.36367 L mmHg/(K mol), and "T" is temperature which you must calculate in K by adding 273.15 to 35 °C which gives T = 308.15 K

To find "n" we must use the molar mass. Oxygen = 15.999 g/mol so O₂ is (2)(15.999) = 31.998 g/mol. So 200 mg = 0.200 grams and (0.200 g)/(31.998 g/mol) = 0.0062504 moles

So V = nRT/P = (0.0062504 mol)[62.36367 L mmHg/(K mol)](308.15 K)/(740 mmHg) = 0.16 liters