A large balloon used to sample the upper atmosphere is filled with 760 m3 of helium. What is the mass of the helium (in kg)?

Answer 1

Helium is a gas which is much lighter than air. It has a weight of 4.00 g per mole. I have to assume that we have measured the volume of the helium here on earth. Lets pick T=273 K as the measurement temperature so that we can use the known properties of the the atmosphere and moles of gas. There are 22.4 liters in one mole. There are 1000liters/1 m^3. So, There are 1000 liters / 22.4 liters/mole = 44.6 moles per m^3 which is 178.6 g per m^3. M of He for 760 m^3 is = 135.7Kg