An open vessel at `27^(@)C` is heated until `3//5^(th)` of the air in it has been expelled. Assuming that the volume of the vessel remains constant find
the air escaped out if vessel is heated to 900 K?

Explanation

One should clearly note the fact that on heating a gas in a vessel there are the number of moles of gas which go out, the volume of vessel remains constant.
Let initial moles of gas at 300 K be ‘n’. On heating 3/5 moles of air are escaped out at temperature T.
`:.` Moles of air left at temperature `T =(n-(3)/(5) n) = (2n)/(5)`
On heating vessel to 900 K, let `n_(1)` moles be left again `n_(1)T_(1) = n_(2)T_(2)`
`n_(1) xx 900 = 300 xx n rArr n_(1) = (1)/(3)n " " :.` Moles escaped out `=n - (n)/(3) = (2)/(3)n` moles