Homework Help: Helium balloon problem adiabatic process

1. Dec 15, 2012

kellya55

1. The problem statement, all variables and given/known data

A large research balloon containing 2000 m^3 of helium gas at 1.00 atm and a temperature of 15.0 celsius rises rapidly from ground level to an altitude at which the atmospheric pressure is only 0.900 atm (the figure (Figure 1) ). Assume the helium behaves like an ideal gas and the balloon's ascent is too rapid to permit much heat exchange with the surrounding air.Calculate the volume of the gas at the higher altitude?Calculate the temperature of the gas at the higher altitude?

T1V1^gamma-1=T2V2^gamma-1 where gamma is 1.67 for helium

3. The attempt at a solution
Found volume of helium to be 2130 m ^3 which was correct but then kept on getting a temperature of around 3.-3.3 celsius(answer is to be given in celsius)using different vales for atm and gamma.It says that my rounding is off so I'll give step by step procedure of what I did
288.15 x 2000^0.67=T2 x 2130^0.67

2. Dec 15, 2012

ehild

The temperature can be obtained easier (and with less error) using the ideal gas law:

PV/T=const.

The value for the new temperature is 3.1 °C.

ehild