Convertion from weight percent on to mole percent 1

[Melimelo]

Hello!
I have the solution, but just to be sure:

Could you remember me the conversion from weight percent on to mole percent (for gases)?

Thank you so much!

 

[Latexman]

Why don't you submit the solution and we'll tell you if it's right or not.

Good luck,
Latexman

 

[Melimelo]

You're funny! ;o) But OK!

Well, we know that for a composant i: ni=mi/Mi

So, if for example, we have just 3 composants:

n1%=((m1%/M1)/((m1%/M1)+(m2%/M2)+(m3%/M3))

The same to find n2% and n3%

Is it right? )))

(Sorry for my bad English...)

 

[25362]

If m_i is mass, M_i is molecular weight, and n_i is moles of component i, then your procedure is correct.

 

[Melimelo]

Yes, it is! )
Thank you very much 25362!
But, i would prefer to have the opinion of Latexman as well!!! ;o)

 

[Latexman]

You are not very thorough either. You should define the variables n, m, and M because not everyone uses the same textbook. However, if I ASSume:

n = moles,
m = mass, and
M = molecular weight,

you are somewhat correct. Your equation will give you mole fraction, not mole %.

In the future if you strive to make it easy for people to answer your questions, you'll get much faster and better responses. Define your assumptions and variables, show us your data and equations, and if it is somewhat complez, attach a drawing.

Good luck,
Latexman

 

[Melimelo]

Well, you're right and you guessed well! )

n = moles;
m = mass;
and M = molecular weight

My answer were not really thorough but I was in a hurry!!
I didn't want you to think that I didn't have any solution (I joke).
Anyway, again, you're right and thank you for advices!!

Méli )

 

[Melimelo]

Is this site is American or English?
I'm French and I would like to know if I can ask my questions both in French and English as my English is not so good...
Thank you!

 

[Latexman]

It is American. I've only seen posts in English here. Your English seems fine to me. I've seen a lot worse here and communication was still possible.

Good luck,
Latexman

 

[Melimelo]

OK, thanks Latexman!
Anyway, it's a good way for me to improve my technical English...
By the way, I'm a beginner process engineer and begun my first work (with a lot of fear and not enough self-confidence) in a engineering gas company since 3 month )
So, it's why my questions are and could look basics...
Happy to have found this excellent forum!
See you...

 

[Latexman]

M[è]li,

It is my pleasure. I've been a practicing Chemical Engineer for about 30 years, and some of the basics have been engraved into my brain by now.

The reason I ask that questions be thorough is most of us have full time jobs and we cannot spend a lot of time answering them, so the more effort the questioner puts into it, hopefully, the better and faster the advice. I know I skip a lot of questions I could answer, because they would just take too much of my time.

Au revoir.

Good luck,
Latexman

 

[Melimelo]

Hello Latexman!

Thank you for your answer and sorry for being late to reply, I didn't use eng-tips.com this week-end...)

Waw, you have been chemical engineer for 30 years!!! Congratulations! It's my first 3 months in my job and I am so afraid!!!
In the same time, I'm very happy because it looks very interesting!

Normaly, when I was still at school, I was a pretty good student but on the job, things looks different and sometimes (just sometimes) harder...

I think I will come back sometimes to this forum to ask my stupid questions! )

Oh, by the way, I have one:
When I want to design any equipment, we define the OPERATING (which are the real ones) and the DESIGN (which are with 5% or 10% more to the operating ones) values of T and P.

I thought that :
OPERATING values = DESIGN values
OVERDESIGN values = DESIGN values + 5/10%

But I think it's false...My boss (who was not very happy of me today) said to me:

OPERATING values = Real values found in calculations
DESIGN values = OPERATING values + 5/10%

What do you think?
As concerning me, I am pretty sure he will fire me before my trial period is over, although I am doing my best for not doing any mistakes but there are so many subtleties...(

See you,
Méli

 

[Latexman]

First, start a new post for a new question. Otherwise, it makes it difficult to search the old posts if they have multiple topics and the title is about the first topic.

Good luck,
Latexman

 

[Melimelo]

Again, you're right!
It's done! I have put another topic!
See you,
Méli )