How Big is the Balloon When Helium Tank Pressure Drops?

[gabriel5]

Homework Statement

Helium in a steel tank is at 250kPa, 300K with a volume of .1m^3. It is used to fill a balloon. When the pressure drops to 150kPa, the flow of helium stops by itself. If all the helium is still at 300k, how big balloon is produced?

Homework Equations

I used the ideal gas law PV=mRT

The Attempt at a Solution

What i did was that i solved for the mass which i got was .04012 and then i used that mass in the ideal gas law with the new pressure of 150kPa to get a new volume of .167 m^3 is this the right approach and answer?

 

[Doc Al]

That's a fine approach, but be sure to answer the precise question asked: How big is the balloon?

Rather than calculate the mass, since it's constant, you could have just used:
P₁V₁ = P₂V₂.

 

[gabriel5]

By asking how big the balloon is doesn't it mean give the volume or what do you think i should put down?

 

[Doc Al]

You want the volume of the balloon, not the total volume.