A spherical balloon can hold 1.2 liters of helium. The balloon has a mass of 26 milligrams when empty. Helium has a density of 0.1785 grams per liter. What is the mass of the balloon when it is filled with helium?

1 Answer
anor277
May 21, 2016

#"Mass of full balloon "=" Mass of empty balloon + mass of contents"# #=# #??g#

Explanation:

So, we need first to calculate the mass of the helium in the balloon.

We are told that there are #1.2*L# of #He#, and also that the density (#rho#) of #He# #=# #0.1785*g*L^-1#.

But #rho# #=# #"Mass"/"Volume"#. Thus #"Mass of gas"= " Volume"xxrho# #=# #0.1785*g*cancel(L^-1)xx1.2*cancelL# #=# #0.2142*g#. Note here that the units I used cancelled out to give an answer in grams as required.

Given this mass, the mass of the balloon is this mass + tare value #=# #0.2142*g+ 0.026*g#. Capisce? If I let it go, will it float or sink in the air; why?

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