question_answer 1)

A student forgot to add the reaction mixture to the round bottom flask at \[27{}^\circ C\]but put it on the flame. After a lapse of time, he realised his mistake. By using a pyrometer, he found that the temperature of the flask was\[477{}^\circ C\]. What fraction of air would have been expelled out?  

Answer:

In an open vessel, pressure and volume are always constant. Thus, we can use \[{{n}_{1}}{{T}_{1}}={{n}_{2}}{{T}_{2}}\] \[x\times 300={{n}_{2}}\times 750\] \[{{n}_{2}}=x\times \frac{300}{750}\] \[{{n}_{2}}=x\times \frac{2}{5}\] 2/5th of the gas is remaining, hence 3/5th gas would have been expelled out.