A helium-filled balloon at sea level has a volume of 2.3 L at 0.987 atm and 34°C.

Question

If it is released and rises to an elevation at which the pressure is 0.900 atm and the temperature is 31°C, what will be the new volume of the balloon?

Answer 1

Use:

where p₁ = 0.987 atm, v₁ = 2.3 L and T₁ = (34 + 273) or 307 K

and where p₂ = 0.900 atm, T₂ = (31 + 273) or 304 K

(0.987)(2.3)/307 = (0.900)(v₂)/304

Cross multiply to get:

(0.987)(2.3)(304) = (0.900)(307)(v₂)

Divide both sides by (0.900)(307) to get:

v₂ = [(0.987)(2.3)(304)]/[(0.900)(307)]

v₂ = 2.5 L