Question in desciption

Question

A typical high-pressure cylinder of helium contains 200 grams of the gas. If all the gas is used to inflate 5-liter part balloons, how many balloons could you fill? Assume the balloons are at STP. (It's a cold day at the kid's birthday party)

Answer 1

We will need to know how many moles we have of He gas. Beginning with 200 grams and dividing by the molar mass (from the perioding table) we get:

(200 g)/(4.003 g/mol) = 49.963 moles

Now, let's calculate the volume of that gas at STP using the Ideal Gas Law:

PV = nRT

V = nRT/P

n = 49.963 moles

STP means a T = 273.15 K and P = 100 kPa

Looking up "R" in appropriate units we find R = 8.31446 L•kPa/(K•mol)

So:

V = (49.963)(8.31446)(273.15)/(100) = 1134.7 liters

Each balloon is 5 liters so 1134.7/5 = 226.9 balloons so we can fill 226 balloons and have some left over to not quite fill another