Question

What mass of helium is in a 2.00-L ballon at STP?

I know this is a question I should ask in Chemistry but in the Chemistry section nobody will answer. Please help I will medal.

Answer 1

*balloon

Answer 2

First find the number of moles of helium. One mole of gas occupies 22.41 L at STP. You have 2L. So how many moles are there?

Answer 3

Once you have the number of moles, then just multiply number of moles by the atomic mass of helium, from the periodic table.

Answer 4

STP literally means Standard Temperature and Pressure. So you should memorize what these are, look them up!

Now you have the ideal gas equation PV=nRT

T and P we just discussed, you were given the volume in Liters so V is taken care of, R is the gas constant so that is something you can look up as well. So you can solve directly for n, the number of moles of Helium!

Moles is just a unit for counting things that come in large numbers, just like 1 dozen eggs is 12 eggs, 1 mole of eggs is about \(602000000000000000000000\) eggs. If you know how much one egg weighs, then you multiply the amount of eggs you have by the weight of that single egg to know how much mass of eggs you have altogether. It's much simpler to think about eggs imo.