You breathe in 6. 0 L of pure oxygen at 298 K and 1,000 kPa to fill your lungs. How many moles of oxygen did you take in? Use the ideal gas law: PV = nRT where R=8. 31 L−kPa/mol−K 0. 05 mole 0. 41 mole 2. 42 moles 20. 0 moles.