# Electric Charge of a Gas

1. Sep 7, 2008

### just.karl

A container holds a gas consisting of 1.75 moles of oxygen molecules. One in a million of these molecules has lost a single electron. What is the net charge of the gas.

1.6 x 10^-19(C/e^-) x n(e^-)

So I'm looking for the number of electrons (n) which I think is 1.05625 x 10^19 and the final answer would be .169C. "Working backwards from the answer in the back" but I do not understand how I would figure out the number of electrons. Help?

2. Sep 7, 2008

### alphysicist

Hi just.karl,

How many molecules of oxygen are in 1.75 moles?

3. Sep 7, 2008

### just.karl

10.538 x 10^23 molecules ?

4. Sep 7, 2008

### alphysicist

I think that's right, so you know how many total molecules there are. Do you see what to do now?

5. Sep 7, 2008

### just.karl

Yeah, then I just divide that by 1 x 10^6 to get the number of electrons, then plug it into the original equation. Thanks!! I really appreciate your help

6. Sep 7, 2008

### alphysicist

Glad to help! But remember that you weren't really counting electrons; that number was the number of oxygen molecules that had one more proton than electrons. (But the proton charge magnitude is the same as the electron charge magnitude.)

7. Sep 7, 2008

### just.karl

I thought that I was counting the number of molecules that are missing a electron and what the charge of the gas is without them?

8. Sep 7, 2008

### alphysicist

That's exactly right. I must have just misread some of your statements.

9. Sep 7, 2008

### just.karl

lol alright, I probably mis wrote some of the statements. Thanks again!