Question

A weather balloon is inflated with helium to a volume of 28.1 L at a pressure of 754 torr and a temperature of 26.0 Celsius. The balloon rises in the atmosphere to an altitude where the pressure is 380 torr and the temperature is -16.1 degree Celsius.

1. Calculate the number of helium atoms per liter for both altitudes.


Is it 2.44 x 10^22 He atoms per liter?


2. Calculate the gas density (g/mL) for each altitude (AW He= 4.00 g/mol).

Answer 1

1 no.
PV = nRT and solve for n = number of mols. Then n x 6.022E23 = number He atoms. Same at both temperatures.

2. density = P*molar mass/RT gives density in g/L. Convert to g/L.