# Help with the pressure problem

1. Jan 23, 2009

### Heila

i need help with this two problems

1. The problem statement, all variables and given/known data

calculate the pressure of 3.2gm of O2 gas in acontainer its volume 4000ml at 100oC knowing that the molucul mass for O2 = 16u

2. Relevant equations

3. The attempt at a solution

PV=nRT
P=3.2x8.314x373x1000000 /(16x2x4000 )

1. The problem statement, all variables and given/known data

At atmospheric pressure and at 0oC and the molecule mass for Nitrogen is 28 u so the volume for 1Kg mol equal

2. Relevant equations

3. The attempt at a solution

PV=nRT
V = 273x8.314 /28x1.o13x105

2. Jan 23, 2009

### LowlyPion

Welcome to PF.

What do you seem to be having trouble with?

What units are your answers supposed to be?

3. Jan 23, 2009

### Heila

I just want to know if my answer in correct

for the first problem 'Pa' and the second 'm3/Kg mol'

4. Jan 23, 2009

### LowlyPion

The first one looks like it is set up OK for Pa.

Volume though is generally given as m3 or L.

I'm not sure what you mean by "m3/Kg mol"

5. Jan 23, 2009

### Heila

so it is o.k if i just used m3 right ..??

thanks for your help

6. Jan 23, 2009

### LowlyPion

I'd say it is set up OK for finding the volume of 1 kg of N gas, if that is the question.

But I hesitate with your statement "the volume for 1Kg mol equal "

7. Jan 23, 2009

### Heila

sorry I'm lost here ..
you mean if the question says the volume of 1 kg of N gas then m3 is correct, but what about is the question says the volume for 1Kg mol equal then is it o.k if i used m3/Kg mol or not ..

8. Jan 23, 2009

### LowlyPion

I was merely pointing out that the statement of the problem is suggesting something different.

1 kg mol of a substance is 1kg*Molecular mass.

So for your problem with Nitrogen at 28, this suggests that you would use 28 kg of gas, not 1 kg.

Your answer looks to me like it's off by a factor of 28.