Find the number of molecules per unit volume of oxygen at NTP. [Mass of an oxygen molecule = ` 5.313 xx 10^(-26)` kg, rms speed of oxygen molecles at NTP = 461.2 m/s]

Explanation

` p = 1.013 xx 10^(5) N//m^(2)`
`p = 1/3 (Nm_(0))/(V) c_(rms)^(2)`
The number of molecules per unit volume,
` N/V = (3p)/(m_(0) c_(rms)^(2))`
` (3xx 1.013 xx 10^(5))/(( 5.313 xx10^(-26)) (461.2)^(2))`
` 2.689 xx 10^(25) ` moleclules / `m^(3)`