A 5.00 Liter balloon contains He gas at a pressure of 740mm Hg. What is its new pressure, assuming no change in temperature, if the volume of He is changed to 1.25L.

Question

anonymous · Answer

Using the perfect gas equation PV = nRT, let's find the change.
So going forward, we have n remaining the same since no new substance were added. R is also the same insce that's the constant, and T is the same as well. 

Now you know that the entire otherside of the equation does not change. but since both of the PV equals to the same nRT, they're also equal to each other

might be a lil confusing, so lemme lay it out in equation, just keep in mind:
nRT = nRT, the nRT does not change

$$P_{1}V_{1} = nRT = P_{2}V_{2}$$

I hope that clears it up. so now we know, PV = PV

insert them into the equation ,the only thing that's unfilled would be the second pressure! In which case, solve for P!

anonymous · Answer

so i would set up the equation 5.00*740=1.25*x

anonymous · Answer

Seems to be the case.

anonymous · Answer

cool that helps alot

anonymous · Answer

Just make sure you understand why things are happening, assuming you are taking the AP exam. Solving the problem is an easy task once you got that.

anonymous · Answer

Thanks for the medal. Good luck in chem.