# Pressure Question: Ideal Gas

1. Oct 29, 2006

### cheechnchong

Problem: An oxygen sample of 1.62 L is at 92.3 kPa and 30.0 degrees celsius.

(a) What volume would the oxygen occupy if the pressure was 120.0 kPa and the temperature was 0.0 degrees celsius.

(b) How many moles of oxygen are in the sample?

My Approach:

Conversions: 0 degrees celsius = 273k
30 degrees celsius = 303k
92.3 kPa = .911 atm
120.0 kPa = 1.18 atm

(a) PV = nRT
(.911 atm) (1.62 L) = n (.08206 l*atm/mol*k) (303k) --- finding n from given information

n = 0.0594 mol

then, i plug that n into

PV= nRT ---using second set of given information
(1.18 atm) V2 = (0.0594 mol) (.08206 l*atm/mol*k) (273k)

V2 = 11.3 L

(b) 0.0594 mol O2 ( this was figured earlier)

Anyways, I'd like someone to check my work here!!! THANKS!

2. Oct 29, 2006

### Smith4046

Maybe I'm wrong, but I'd check your last step (multiplication & division) just before determining V2. Think you might be off by a factor of 10.

I used the combined gas law:

P1V1/T1 = P2V2/T2 and ended up with 1.13L

Also, from the original conditions, isn't the P increasing and the T decreasing. Shouldn't that lead to a decrease in volume from the original 1.62L?

Hope I am right here. Like I said in an earlier message - I haven't taken a chemistry course in over 3 decades.

Best of luck.

Steve

3. Oct 29, 2006

### cheechnchong

hey good look...errrrrr my calculator skills are horrible LOL big thanks!