An oxygen cylinder of volume 30 litres has an initial gauge pressure of 15 atm. And a temperature of `27^(@)C`. After some oxygen is withdrawn from the cylinder, the gauge pressure drops to 11 atm. And its temperature drops to `17^(@)C`. Estimate the mass of oxygen taken out of the cylinder. `(R = 8.1 J "mole"^(-1) K^(-1)`, molecular mass of `O_(2) = 32 u)`.

Answer

`0.139` kg

Explanation

No. of moles withdrawn = `n_(1) -n_(2) = (Deltam)/(M)`
`implies Deltam = M(n_(1) - n_(2)) = M((P_(1)V_(1))/(RT_(1)) - (P_(2)V_(2))/(RT_(2)))`
= `32[(15 xx 10^(5) xx 30 xx 10^(-3))/(300 xx 8.314) - (11 xx 10^(5) xx 30 xx 10^(-3))/(290xx 8.314)]`
=`0.139` kg