Assuming the same pressure in each case calculate the mass of hydrogen requied to inflate a ballon to a certain volume `V` at `100^(@)C` if `3.5 g` helium is required to inflate the balloon to half the volume `V` at `25^(@)C` .

Explanation

Volume of 3.5 g He at `25^(@)C` and pressure P,
`V=(nRT)/(P)=(w)/(M)(RT)/(P)=(3.5)/(4)xx(Rxx298)/(P)`
To fill the balloon with `H_(2)` to double this volume means volume of `H_(2)`=V, T=373 K. Hence,
`2V=(w)/(M)(RT)/(P)=(w)/(2)xx(Rxx373)/(P)`
Dividing (ii) by (i) we get `2=(wxx373)/(2)xx(4)/(3.5xx298) " or " w=2.796%" g"`