Hi people, I'm currently handling my final year project. and I need to calculate the no. of moles of dimethyl ether produced, using both the peak area (GC) and response factor. Is it possible that anyone out there can teach me how to go about doing it? I have the following details:
-response factor
-relative response factor (relative to carrier gas; helium)
-all relevant peak areas (He, meOH, DME, CO, CO2 & H2O)
-vol. of gas injected
-no. of moles of He & meOH (initial)

Thank you! & God Bless!

And I only thought you could analyze using GC, I didn't know you could produce DME using Gas Chromatography!
Homework should be performed at home using your own brain. My understanding, YOUR Final project.

If you have a response factor for DME, and peak area from your chromatogram, you should be able to calculate the concentration or weight of DME injected, from which you should be able to calculate the moles.

To the first 'anonymous', I'm afraid you do not understand my question. I do not produce DME using GC, I analyse DME using GC. Of course I know that this is my final year project. But from my understanding, this is a forum that let people discuss ways to solve problems. And now, that I'm facing a problem, I just hope that some kind hearted people would give some suggestion to solve the problem.

To the second 'anonymous', thank you for your suggestion. And you are kind enough to provide me with that. But probably I'm using the wrong method, because I keep getting negative answers. Hopefully you can help me with some hints. Your kindness is definitely appreciated.

What means negative answers?
Is there possibility of hydrolysis your DME?
Final year project is work, that you have to
do to become diplomaed?

Were the relative response factors determined from weights, moles, volumes, partial pressures, something else? I am used to relative response factors being determined from weights but since you are dealing with gasses, I suppose there are other ways they could have been determined which would change your calculations.

To the third 'anonymous', you are right. If I flunk this project, I would not get my Dip. What I meant by negative answer is that I tried to find out the no. of moles of methanol reacted, by deducting the no. of moles of methanol detected during analysis from the initial no. of moles, which is calculated using Antoine Eqn, and Ideal Gas Law.
But when I calculate, the no. of moles detected during analysis is even bigger than my initial no. of moles, thus the negative answer. I calculate the no. of moles detected using the ratio of area of methanol over area of helium, multiply by the ratio of response factor of helium over response factor of methanol.

To Russ. The RRF I had was determined using the response factors provided by my lecturer. As helium is my carrier gas, I use it as a reference. So all my RRFs were determined by dividing the RF of my reference with the RF of the respective compounds.

I guess I'm confused. You are using helium carrier gas, but you have a helium peak in your chromatogram?

-all relevant peak areas (He, meOH, DME, CO, CO2 & H2O)

1.Your calculation of the no. of moles detected contains an error.
You are getting answer in the no. moles of methanol per no. of moles
of helium. It is concentration unit. You should multiply it by the no.
of moles of helium.
2.Make sure your response factors were calculated from moles.
3.It would be better to calculate response factors from calibration.
You can just analyse your reaction mixture at initial point of
reaction.

How do you run the reaction?
Is it periodical or uninterrupted?
How do you transfer the sample from reactor
to GC?

Advise of second anonymous was good enough.

Cherylnn -
You are experiencing "hostility" from some members of this group because we feel that students should do everything they can to research and solve the problem on their own. When you get out of school, you will have colleagues to brainstorm and help in difficult situations, but it is expected that you do your own work. When you post your question in this forum, it is perceived that you want us to do your work for you and you will never learn how to think or research a problem for yourself. That is a dangerous habit to acquire. You won't succeed if you expect others to do your work for you. Good luck with your project and I hope you have learned from everyone's comments.

Hi people, I've finally found out whats wrong with my calculation, through the help of certain reference books that my school library ran out of sometime ago. I hope to clarify that in the very first place, expecting people to do my work for me was definitely not what I wanted. All I needed was a little help such that I would know what's the problem, as those reference books were all borrowed out. I do not in the very first place require people to do my work for me. I just needed some guidance. But nonetheless, thanks to all the above 'anonymous', and russ for your help and kindness. I sure learn one thing, Never Ever post my doubts or questions here stating that I needed help because I'm facing problems with my academic modules. Just ask it in any other normal way that people do, and no one would accuse me of trying to get people to do my work. That's because I strongly believe that any other people who post their questions or doubts in this forum, face problems, be it in their academic or work.
And by the way, I did do my own work. I did not offer to pay anyone to do my work for me, and then email it back to me.