If I fill a balloon with helium it will float. Why does it float? Estimate the mass of helium in the balloon.

It only makes objects float if they are less dense than their surroundings, like a boat on water, or a helium balloon in air. Buoyancy works due to displacement. ... In the case of a balloon, the helium inside the balloon weighs less than the same volume of air the balloon displaces

Explanation:

In the case of a balloon, the helium inside the balloon weighs less than the same volume of air the balloon displaces. ... So a helium balloon has two opposing forces acting on it: gravity pulling it down, and buoyancy pushing it up. Buoyancy wins, so you can't really weigh a balloon, even though it does have weight.

Knowing the volume of air displaced by the helium balloon, we can calculate the maximum mass the balloon can lift. ... Helium, which has a mass of 4.00 g/mol, has a density of 0.164 g/l. Thus, a one-liter balloon of helium can lift a mass of (1.18-0.164) = 1.02 g.