Question #10db8

1 Answer
Jun 20, 2017

2.8 * 10^82.8108 "g"g

Explanation:

The thing to remember about the density of a substance is that it represents the mass of exactly one unit of volume of said substance.

"density" = "mass of substance"/"1 unit of volume"density=mass of substance1 unit of volume

In your case, the density of helium at STP is equal to "0.1875 g L"^(-1)0.1875 g L1, which means that under STP conditions, every "1 L"1 L of helium has a mass "0.1875 g"0.1875 g.

"0.1875 g L"^(-1) = "0.1875 g"/"1 L"0.1875 g L1=0.1875 g1 L

Now, you know that the volume of the balloon is equal to 1.5 * 10^91.5109 "L"L under STP conditions.

Since you already know that you get "0.1875 g"0.1875 g of helium per "1 L"1 L, use the density of the helium at STP as a conversion factor to find the mass present in your balloon

1.5 * 10^9 color(red)(cancel(color(black)("L"))) * overbrace("0.1875 g"/(1color(red)(cancel(color(black)("L")))))^(color(blue)("the density of helium at STP")) =color(darkgreen)(ul(color(black)(2.8 * 10^8color(white)(.)"g")))

The answer is rounded to two sig figs, the number of sig figs you have for the volume of the balloon.