Why Do Helium Filled Balloons Float?
Helium is an element, atomic number 2, atomic weight 4.003. It is lighter than air, and is used to fill balloons because they will rise, whether party balloons, weather balloons, gas balloons (for travel) or blimps. This is due to helium’s lower-than-air density. Ideal Gas Law More than a century ago, the basic gas laws were derived. These laws relate pressure, mass and volume. The Ideal Gas Law reads, pV = nRT This law says pressure times volume of a gas V, is equal to the “moles” of the gas n, times a constant R, times its temperature T. What are moles? Moles equal the weight of a gas divided by its molecular weight. The gas law becomes, pV = (w/mw) x (RT) Pressure times Volume = Weight divided by Molecular Weight times constant R times temperature T Now let’s rearrange this formula so that only the weight and the volume are on the left side of the equation and everything else is on the right side. We get the result, w/V = (p/RT) x mw Comparison to Water Consider a swimming pool of w
