A balloon is filled with 0.75 L of helium gas at 1 atm pressure and 25 degrees Celsius. The balloon is released and floats upward in the atmosphere. The temperature drops to 23 degrees Celsius and the balloon expands to 1.50 L. What is the pressure at this altitude? Assume the gas behaves ideally.

Answer 1

(P1V1)/T1 = (P2V2)/T2
Don't forget to use T in Kelvin.

Answer 2

-275.38