Question

The pressure in a vessel that contained pure oxygen dropped from 2000torr to 1500 torr in 40 min as oxygen leaked.when some vessel was filled with another gas the pressure dropped from 2000torr to 1500torr in 80 min.find the molar mass of another gas

Answer 1

Dear student,

The pressure drop = 2000-1500 = 500 torr
Gas is oxygen having molar mass = 16g
In second case, pressure drop = 2000-1500 = 500torr
Rate of diffusions are inversely proportional to molar masses
$$\begin{gathered} \frac{R_{d_1}}{R_{d_2}}=\sqrt{\frac{M_2}{M_1}} \\ \frac{500}{500}=\sqrt{\frac{M_2}{16}} \end{gathered}$$
Squaring both sides and calculating we get
M₂ = 16g

Regards