Question

Calculate the % empty space in 100 mL of air. You can use the ideal gas law, Avogadro's number, and the average volume of O2 and N2 (3.8 x 10 ^24 cm^3/molecule).

Answer 1

calculate total number of molecules in 100 ml of air or 0.1 L...

PV = nRT

assume STP condition sso

22.4 L --> 1 mol

then

0.1 L --> 0.1*1/22.4= 0.00446428 mol

1 mol = 6.022*10^23 molecules

then

0.00446428*6.022*10^23 = 2.68838*10^21 molecules of N2+O2

since average sace is

V = 3.8*10^24 cm3/molecule and 2.68838*10^21

NOTE: the sapce occupied per molecules shoudl be very very little, im sure the 3.8*10^24 is actually  3.8*10^-24

V = ( 2.68838*10^21)(3.8*10^-24) = 0.010215844 cm3 or ml

then

% = occupied / total *100 = 0.010215844 / 100 * 100 = 0.010215844%