A student forgot to add the reaction mixture to the round bottomed flask at `27^@C` but put it on the flame.After a lapse of time, he realized his mistake. Using a pyrometer he found the temperature of the flask was`477^@C` fraction of air would have been expelled ?

Explanation

Suppose the number of mol of air inside the flask at `27^(@)C` is `n_(1)` and that at `477^(@)C` in `n_(2)`. Since the flask is opened to air, the pressure of aiir iniside the flask at `27^(@)C and 477^(@)C` is the same as that of the atmospheric pressure. let this pressure be P. again on heating the volume of a round bottom flask remains the same. hence, the volume of the flask is the some at both `27^(@)C and 477^(@)C`. let this volume be V.
Applying ideal gas equation we have, PV=`n_(1)R(273+27)`
`=n_(1)xx300R&PV=n_(2)R(273+477)=n_(2)xx570R`
Hence, `n_(1)xx300R=n_(2)xx750R` or, `n_(2)=(2)/(5)n_(1)`
`therefore`Fraction of air that would have been expelled out`=(n_(1)-(2)/(5)n_(1))/(n_(1))=(3)/(5)`