a sample of oxygen, helium-filled ballon?

Question

A sample of oxygen gas occupies a volume of 7.02 L at 52.0°C and 0.650 atm.

If it is desired to decrease the volume of the gas sample to 4.59 L, while increasing its pressure to 0.800 atm, the temperature of the gas sample at the new volume and pressure must be ______°C.

A helium-filled weather balloon has a volume of 558 L at 19.9°C and 755 mmHg. It is released and rises to an altitude of 5.35 km, where the pressure is 463 mmHg and the temperature is –14.1°C.

The volume of the balloon at this altitude is _____ L.

Answer 1

You know initial pressure, volume and temperature. You know the final volume and pressure, and are asked to find the final temperature. For this, we use the combined gas law, P1V1/T1 = P2V2/T2 using temperature in Kelvin.

(0.650 atm)(7.02 L)/325K = (0.800 atm)(4.59 L)/T2

T2 = (0.800)(4.59)(325) / (0.650)(7.02)

T2 = 262K

T2 = 262 - 273 = -11ºC

P1V1/T1 = P2V2/T2

(755 mm)(558 L)/292.9 = (463 mm)(V2)/258.9

V2 = (755)(558)(258.9) / (463)(292.9)

V2 = 804 L