Question

A balloon filled with helium rises to a certain height at which it gets fully inflated to a volume of $1\times {10}^5$ litres. If at this altitude temperature and atmospheric pressure is $268K$ and $2\times {10}^{-3}atm$ respectively, what weight of helium will be required to fully inflate the balloon?

Answer 1

$V=1\times {10}^{5}lit$

$T=268K$ & $P=2\times {10}^{-3}atm$

Let $w$ is the wt of $He$ required inflating the balloon

$PV=\frac{W}{M_{He}}RT$

$2\times {10}^{-3}\times {10}^5=\frac{w}{4}\times 0.0821\times 268\Rightarrow w=\frac{2\times {10}^2\times 4}{0.0821\times 268}=36.36g$