Question

3. A helium filled balloon has a volume of 39.0mL at 17C and the current atmospheric pressure is reading 802mmHg on the barometer. What volume will the helium gas take up when the pressure reading on the barometer drops to 637mmHg and the temperature plummets to 7C?

Answer 1

.0466 L

Step-by-step explanation:

To start off, use dimensional analysis to convert everything to standard PV=nRT units.

`(39.0)/(1)` x
`(1)/(1000)` = .039 L

`(802)/(1)` x
`(1)/(760)` = 1.055 atm

17 +273 = 290

...and so on.

Solve for n for the starting pressure, volume and temp. You'll need it for the final equation.

n= PV/RT
`(1.055 *.039)/(.0821 * 290)`= .0017 number of moles

Solve for volume of the end point.

V= nRT/P
`(.0017*.0821*280)/(.838)` = .0466 L of helium, or 46.6ml Less pressure means it will take up more space.