Question

(a) How much $H_2$ (in mol) is needed to inflate a balloon of radius $3m$ to a pressure of $1atmp$ in an ambient temp at ${25}^{\circ }C$ at sea level.
(b) What mass can the balloon lift at sea level, where the density of air is $1.22Kg{m}^{-3}$
(c) What would be the pay load if $He$ were used instead of $H_2$.

Answer 1

(a) Volume of the spherical balloon = $\frac{4}{3}\ast 3.14\ast 3\ast 3\ast 3$ = 113.142 $m^3$ = 113142.85 L

moles of $H_2$ = 5142.85 moles

(b) 1 $m^3$ have mass = 1 Kg

1000L of gas have mass = $1/1000$ Kg

mass of 5142.85 L of gas = 5.1428 L

(c) when He is used in place of $H_2$ then pay load will be same because at NTP,all gases of equal moles have same volume.