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 3.5g He at `25^(@)C` and pressure P, `V = (nRT)/(P) = (W)/(M) (RT)/(P) = (3.5)/(4) xx (R xx 298)/(P)` ….(i)
To fill the balloon with H2 to double this volume means volume of H2 = 2V, T = 373 K. Hence,
`2V = (W)/(M) (RT)/(P) = (W)/(2) xx (R xx 373)/(P)`, Dividing (ii) by (i) we
`2= (W xx 373)/(2) xx (4)/(3.5 xx 298) or w = 2.796g`