# Helium and Balloons/Pressure

1. Dec 2, 2007

### sun

[SOLVED] Helium and Balloons/Pressure

1. The problem statement, all variables and given/known data

A tank having a volume of 0.100 m3 contains helium gas at 120 atm. How many balloons can the tank blow up if each filled balloon is a sphere 0.300 m in diameter at an absolute pressure of 1.35 atm?

What i know:
V(tank)=.1m^3
P(tank)=120atm=1.21E7 Pa

Density(balloon)=.3m
Volume(balloon)=.0141m^3
P(balloon)=1.35atm=1.36E5 Pa

Volume(helium)=1.23E-26 m^3

PV=nRT

So, once the helium is transfered into a balloon the volume it takes up changes due to the change in pressure, correct? I'm not sure how to relate all these quantities in order to find out how many balloons I can fill the the with the given volume of He.

Any suggestions?

Thanks

2. Dec 2, 2007

### Dick

What's the volume of 0.1m^3 of helium at 120 atm if you reduce it to 1atm. Then how many balloons can you fill?

3. Dec 2, 2007

### sun

1.21E7Pa (.1m^3)=1.36E5Pa (V)=629 ballooons

thank you