A question of...Maths!
A question of...Maths!
(OP)
I have a %vol and a %wt composition of a mixture.
I want to calculate the molecular weight of each component.
%vol %wt
Component A 34.8 33.9
Component B 56.8 56.3
Component C 6.0 6.9
Component D 1.0 1.1
Component E 1.4 1.8
Can someone help me? I am trying with a 6 equations system but the last one is not correct, 5 equations for each component and the other...I don't know. I have tried the sums but I don't get anything..
Thank you,
AndreChE
I want to calculate the molecular weight of each component.
%vol %wt
Component A 34.8 33.9
Component B 56.8 56.3
Component C 6.0 6.9
Component D 1.0 1.1
Component E 1.4 1.8
Can someone help me? I am trying with a 6 equations system but the last one is not correct, 5 equations for each component and the other...I don't know. I have tried the sums but I don't get anything..
Thank you,
AndreChE





RE: A question of...Maths!
If it is a gas, I get the following:
Cmpt A is 4.1759
Cmpt B is 4.2490
Cmpt C is 4.9300
Cmpt D is 4.7157
Cmpt E is 5.5123
These are (to coin a phrase), the lowest common factor for MWs. If all of these are multiplied by the same number, eg 10, you would get the same wt% when you converted from vol% to wt%.
On the other hand, with those MWs, they could be various sour H2 streams.
RE: A question of...Maths!
%vol %wt Mol. wt. %vol*MWi %wt*MWtot squared error
Component A 34.8 33.9 0.97 33.90 33.90 1.E-10
Component B 56.8 56.3 0.99 56.30 56.30 3.E-10
Component C 6 6.9 1.15 6.90 6.90 4.E-12
Component D 1 1.1 1.10 1.10 1.10 4.E-15
Component E 1.4 1.8 1.29 1.80 1.80 2.E-13
TOTAL ERROR 4.E-10
Av. mw 1
If you use an average MW of say 30, the table becomes:
%vol %wt Mol. wt. %vol*MWi %wt*MWtot squared error
Component A 34.8 33.9 29.22 1017 1017 1.E-07
Component B 56.8 56.3 29.74 1689 1689 2.8E-07
Component C 6 6.9 34.50 207 207 4.1E-09
Component D 1 1.1 33.00 33 33 1.9E-11
Component E 1.4 1.8 38.57 54 54 1.9E-10
TOTAL ERROR 4E-07
Av. mw 30
Cheers,
Joerd
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: A question of...Maths!
By the way, I had to assume that this is a gas mixture at low pressures (so compressibility z is about 1 for all components, and vol% is same as mol%). Otherwise I would end-up with five more unknowns...
This confirms the post by Joerd above.
RE: A question of...Maths!
How do you do that in Excel?
RE: A question of...Maths!
I would leave well enough alone. You've had 3 good responses to what is a classic student problem in chemistry (not math) and now you not only want a documented answer but also in Excel.
Where are the "thank you" 's? Where are the red flags?
Art Montemayor
Spring, TX
RE: A question of...Maths!
This is not a typical chemistry student problem...believe me!
This is a PIONA... not pure components. It is a problem without a simple solution.
A lot of equations, implicit ones...not a typical chemistry student. General parafins (iso and normal), olefins, naftenics and aromatics!
Thank you all. In this part you are right and I am sorry for that.
AndreChE