Question

A weather balloon is rigid so that its volume is always 525 L and it is filled with 23.7 moles of He gas at a temperature equal to the air temperature that day (-30 degrees celcius).

A. What is the pressure of the helium inside the balloon?

B. If the volume of the balloon is adiabatically compressed to 402 L, what is the pressure inside the balloon?

Answer 1

Volume of ballon is V1 = 525 L, number of moles n = 23.7 molea

           temperature T = -30 0C = 273-30 = 243 k

from ideal gas equation Pv = nRT

           P = nRT/V

           = 23.7*0.082057338*243/525
           = 0.9001455529063 atm

if the volume is compressed adiabatically the the pressure is

P1V1 = P2v2

   P2 = P1*v1/V2
   = 0.9001455529063*525/402 atm

   P2 = 1.1755632 atm

pressure inside the ballon is 1.1755632 atm