# An ideal gas occupies 37 L at 807 torr and 50◦C . What volume would it occupy at STP?

An ideal gas occupies 37 L at 807 torr and

50◦C . What volume would it occupy at STP?

1. 19 L

2. 33 L

3. 31 L

4. 39 L

Relevance

Combined gas law:

P1V1 / T1 = P2V2 / T2

[(807 torr) (37 L)] / 323 K = [(760 torr) (x)] / 273 K

cross multiply

(807 torr) (37 L) (273 K) = (760 torr) (x) (323 K)

Divide

x = 33.2 L (which is answer choice 2)

Source(s): ChemTeam
• There are two ways to approach this. You could use the ideal gas law to calculate moles of gas under the first conditions. Then, knowing that 1 mole of any gas occupies a volume of 22.4 L at STP, you can get to the volume.

Alternatively, you could use the relationship:

P1V1/T1 = P2V2/T2

Either way will work just fine. Remember that temperatures must be expressed in Kelvin.

• use pV = nTR T1= 273.2+50= 323.2K p1 =760 torrs

p1V1 =nRT1 (1) and p2V2=nRT2 (2)

divide (2) by (1) p2V2/P1V1=T2/T1

V2= p1V1T2/T1p2= 807*37*273.2/(323.2*760) =33.2L