Question

A physics lecture room has a volume of 237 m3. (a) For a gas pressure of 1.00 atm and a temperature of 26.0 oC, use the ideal gas law to estimate the number of air molecules in the room. Assume all the air is N2. (b) Calculate the particle density ❝ that is, the number of N2 molecules per cubic centimeter. (c) Calculate the mass of the air in the room.

Answer 1

a) Moles of air molecules= PV/RT

                                                =1.00*237*10³/0.0821*299

                                                =9.655*10³ mol

                Molecules of air=9.655*10³*6.022*10²³=5.814*10²⁷ molecule

b) Molecule density= Molecules/ volume in cm³

                                                =5.814*10²⁷/237*10⁶

                                                =2.453*10¹⁹ molecule/cm³

c) Mass of air= moles of air*mol wt of N₂

                                =9.655*10³*28

                                =270.340 kg