A noble gas is introduced into a flask previously emptied of air with a volume of $ 300 mL$ and a mass of $145.31\;g$. After introduction. the pressure in the tank is $685\;torr$ . the temperature $26\;^oC$ and the mass $146.76\;g$. What gas is it?
$p=\frac{685}{760}\; atm$ $n$ $=$ $\frac{p\;V}{R\; T} $ = $=\frac{685\; 0.30 }{760\; 0.082 \; 299.15}$ $= 0.011$ $M=\frac{m}{n}$ = $\frac{46.76-45.31}{0.011}$ = $131.9\frac{g}{mol}$ It's xenon !
