Performing a Material Balance on a Single Unit

Organized by textbook: learncheme.com/
Performs a mass balance on a distillation column using degree of freedom analysis. Made by faculty at the University of Colorado Boulder Department of Chemical and Biological Engineering. Reviewed by faculty from other academic institutions.
Degree of Freedom Analysis on a Single Unit: • Degree of Freedom Anal...
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Check out our website for interactive MEB simulations: www.learncheme.com/simulations...

[@samskeeytube8829]

This guy is amazing, he explains better than the my lecturer!!!

[@LearnChemE]

This screencast has been reviewed by faculty from other academic institutions.

[@itstwinklerkate]

EDIT: I GRADUATED LAST AUGUST im gonna die sooner or later in chemical engineering

[@seferinahernandez9557]

im a trash me too😭

[@qistina2080]

same dude.. somehow I couldn’t solve this simple calculation 😭😭

[@parkergedwards]

How’s it been

[@hershnotfound]

I feel u bro and im just a freshman

[@erzaaa4580]

i feel u too bro... somehow i wonder how can i end up in the chemical engineering... hahhahahha

[@perezdeveaux3829]

Hi, I was originally confused for the statement "90% of C from m1 in m5", but looking at your calculation, you used 0.40*m5 because stream m5 consists also of B, and not solely component C?

[@anmarsamir4118]

hi ,thanx for explain which book and articles you use

[@siresolace]

Could u guys post the pdf or the slides so I can have access to it thanks

[@bobu5213]

In my chemtech book it says that I can transcribe a molar flow to a concentration times a volume flow? How does this work?

[@emmanuelchibudom9406]

this guy literally just saved my life. literally

[@LearnChemE]

They are random here because I chose two relationships to help us solve the problem. You would need some processing conditions to determine flow rates otherwise the DOF =2 means we are done and there is nothing we can do to solve.

[@geoffreychikwale9532]

Can you solve the problem from Unit In Food Processing 2nd Edition by R. EARLE Chapter 2? The last problem. Thank you. I really have challenges.

[@Hannah_c._]

How did you solve for m1? i don't get it

[@GeorgeWBushDid911]

I feel like this DOF doesn't agree with your DOF video where using something like y=1-x2 counted as an "other equation" please clarify, thanks

[@Bilal626339]

Amazing videos, thank you!

[@user-tc9wl3xx3t]

how did u get the assumption of the 2 specifications??

[@floridazoe2494]

thank you so much, my professor for mass and balance is so confusing

[@noname-zp8sn]

What does the 2nd assumption have to do with the equation??

[@abuayubal-hassan5409]

what does it mean when the balances are not independent

[@mianmubashir_officiall]

Sir why we do overall balance

[@zahidullahnoori6690]

Very nice explanation and very good choice of problem! Do you have a video for problems involving extent of reaction?

[@LearnChemE]

We do! I hope you find these two videos helpful! kzbin.info/www/bejne/lZDWpYCcaLR_hpY kzbin.info/www/bejne/q5_bi4SkpZWsaNk

[@Grandbox1992]

thanks a lot for uploading this video :)

[@hamzadragonball]

The relation m3=0.5m1 and m1(0.9)(0.97)=m5(0.4) are just assumed informations to satisfy the degree of freedom i.e; 2

[@awk2647]

5 years later but thankyou so much. I spent God knows how long trying to figure that out

[@theotherwani8457]

How do we get the statement 'm3 is half the flow rate of m1' and '90% of C in m1 exits in m5' ? or was it given in the question?

[@LearnChemE]

At 4:20 they are presented to help solve the balances. Otherwise the DOF before that revealed it was unsolvable without further information. One reason doing a DOF is important is that in real design you may have to either make assumptions or get more information to proceed.

[@Shishire3210]

LearnChemE This doesnt really answer the questions. You only said that these two relations are known, did not say if they were given or we had to derive them ourselves. Thanks.

[@erikloredo4424]

Shishire3210 he just answered the question the problem would be unsolvable without the introduction of more information. So yes it was given

[@ay91111]

Thanks for explaining that .....can you please explain how to solve that in matrix way ?

[@endless1735]

سحب عليك

[@shmaimat]

Wow ! I understood!!!

[@jonhm2339]

Very good video... but I have a question about the final balance steps. Where is the 2,437 kg/hr coming from? Is there anything being divided? I couldn't figure that step out. Thanks.

[@LearnChemE]

Thanks for your question. The screen at 7:45 lists 5 equations. The first three have three different variables. (3 equations for 3 variables = solvable). After that it is just substitution. m3 = 0.5m1, m5 = 2.1825m1. When you replace the m3 and m5 in equation #3, you get m1 + 5300 = 0.5m1 + 1200 + 2.1825m1. Then you move all of your m1 components to one side to get the equation written to the right. That simplifies to -1.6825m1 = -4100. Then, dividing both sides by -1.6825 you get m1 = 2437 kg/hr. I hope that helps.

[@elliotb1795]

Yeah but it's -0.5-2.1825.... m1 - 0.5 - 2.1825.... How did you turn the 0.5 into a positive all of a sudden? It's a negative on that side of the equation. Should be -0.5-2.1825= -2.6825. Then divide -4,100 by -2.6825.

[@seferinahernandez9557]

I couldn’t understand it too😞

[@imjustsayinmann2457]

yea i dont understand this part, anyone helppp

[@aligujjar7890]

Can someone tell on what basis those 2 assumptions were taken?

[@LearnChemE]

At 4:20 they are presented to help solve the balances. Otherwise the DOF before that revealed it was unsolvable without further information. One reason doing a DOF is important is that in real design you may have to either make assumptions or get more information to proceed.

[@seferinahernandez9557]

Ooh please, can you explain me the ecuation number 3? it gets me headaches 🤯

[@Swimchiclax]

Equation 3 is the overall mass balance, where the total input=total output (all the streams going in equals all of the streams going out for that system). So, you would get stream 1+ stream 2= stream 3+ stream 4+ stream 5. Because the flow rates for streams 2 and 4 are already known to be 5300 and 1200, respectively, you can go ahead and directly plug that into the equation, resulting in m1+5300 = m3 + 1200 + m4.

[@lehakwetloti4947]

Confused What is the justification for 0.5m1=m3 and 0.9(0.97)=0.4m5

[@LearnChemE]

Problem statement facts laid out at 4:19

[@AO-yw3gz]

at 7:15 how did you get m5=1.825m1 i repeated this part more than 10 times and still cant get? i understand the whole Video except this part please help

[@LearnChemE]

+Ali Al-Obaidi I'm confused on your question. At 7:30 in the video, we get m5 = 2.1825m1, just from rearranging equation 2. Are you asking where that information came from? Or just the math?

[@AO-yw3gz]

+LearnChemE yes I am asking about the math

[@LearnChemE]

+Ali Al-Obaidi So the equation starts at 0.90*(0.97m_1) = 0.4m_5 Simplifying the right side: 0.873m_1 = 0.4m_5 Dividing both sides by 0.4: 2.1825 = m_5 The number you gave in your first comment is incorrect. Does that help?

[@sloomegood]

Good example , complet as this example

[@alinajahmusic]

Your tutorial is a bit confusing....how your m1 comes about

[@rockfret]

How did you assume the two relations to make DOF = 0? Is it a total random assumption?

[@nickboomer94]

Check this video if you still doesn't get it. kzbin.info/www/bejne/qoiUl6dqrpqZh7s

[@azyle2104]

Not an assumption, he just gave us 2 things to make it work ( not assumed )

[@azyle2104]

There was no way for us to assume that ... something like that would have to be given information, he gave it to us late to make a point about D.O.F

[@koohamed9219]

Thanks alot

[@nanakstark]

The last 2 conditions flowrate m3is half of M1 how did you get that?

[@LearnChemE]

Those were merely provided to allow you to solve the problem. They weren't calculated. Think of them as just part of the problem statement.

[@nanakstark]

@@LearnChemE I meant the degree of freedom analysis part whether the eqns were given or u calculated them and if calculated then how?😅

[@LearnChemE]

They were given. Once it was discovered that there were 2 degrees of freedom, we needed 2 more pieces of information to solve the problem. So those two items were then given.

[@nanakstark]

@@LearnChemE ohk thnx😁😄

[@macyzoyaf5728]

Isnt there 5 equations? You have 3 species so 3 independent material balances and 2 mass fraction relationships ( 1-x2) and ( 0.30-x4) ?

[@LearnChemE]

As explained around 3:10 in the video, those are not independent relationships. We are using those so that we don't have two further mass fraction unknowns.

[@macyzoyaf5728]

Sorry i feel dumb for asking that hah!

[@louiseanncalairo3949]

Hi... Why isn't m3 1 kg? Doesnt it contain A only?

[@LearnChemE]

Thanks for your question. m3 is the flowrate for the stream. We do know that it is only A, but that is only the composition of the stream, not how much. I hope that helps.

[@chidy90]

Thanx for the video. Just wanna fix a small thing I Think m5 = 5319 kg/h so that what goes in = what comes out.

[@LearnChemE]

Thanks for your comment. They should match up, but the numbers are off by 1 kg/hr likely due to rounding. Since that is less than a 0.02% difference, I wouldn't worry about it.

[@evanjauregui8171]

System of Equations on steroids

[@justaperson3762]

Hi, Im a 2nd year Chem Eng student from the Uk. Im not asking for someone to do my work but what im asking for is just some guidence on a report i need to do. Is there anyone you could recommend me to or get help from. In the report I am required to do a mass balance etc on a process and im really sturggling. Doing online university isnt really helping either. Thanks

[@justaperson3762]

y’all im serious i dont have a clue whats going on someone help 😭😭😭😭😭😭

[@azyle2104]

Hey do you still need it ?

[@justaperson3762]

@@azyle2104 thanks for the reply i actually managed to get something done but my whole class failed the the eng of term exam and we’ll need to resit in june

[@azyle2104]

@@justaperson3762 thats okay though , we all encounter obstacles , smash it !!!

[@NOR-ALSUNA-]

Thanks🥰

[@user-bj3fm6cx2v]

thanks

[@eng.mohammedameensalih2682]

Exclent

[@cindyabundie7916]

Why are the units for mass fraction always written as (X)kg/kg. Isn’t it mathematically accurate to write it as (X)kg/(X)kg since we don’t want to end up with X in our final units.

[@java4235]

this puts UNM to shame

[@samirkhurshid2583]

it will be easier if we have MB on A from the beginning and with just one relation M1+M2 = M3+M4+M5............1 overall MB 2 M3 = M1.............................. 2 relation MB on A : 0,39 M2 = M3 + 0,7 M4............3 since M2 = 5,3 and M4 =1,2 kg/hr so: M3 = 1,227 kg/hr put in 2 so : M1 =2,454 kg/hr put it in 1 so : M5 = 5,327 kg/hr now MB on C : 0,97(2,454) = 0,4(5,327) +1,2 x4 so x4 = 0.2 now MB on B 0,03(2,46) +5.3(x2) = 1,2(0,3- 0,2) +5,327(0,6) so x2 =061

[@LearnChemE]

It is certainly fine to use a mass balance on A to solve the problem. However, I'm not sure how you solve with only one of the relations. In your MB on A, where did you find the fraction of component A in M2? I think that is still an unknown until the problem is at least partially solved.

[@mohamedaminbezzekhami8946]

2,437*0.97=1200X4+5,318*0,4 X4=0,0002 !!! WHY x4= 0,2 ?!

[@LearnChemE]

+Mohamed Amin Bezzekhami The answer in the screencast is correct. I don't follow your math. If we start with 2437*0.97=1200x4+5318*0.4; then we get 2364=1200x4+2127; then 237=1200x4; x4=0.2

[@leiahmariejoyrio7466]

why isnt there a word problem for this :((

[@azyle2104]

You have troubles drawing the diagrams from given information ?

[@salmasalma-qd4dc]

اكو عرب بالطياره😂😂

[@MonkeyDPickle]

can you at least do the math instead of just brushing over it... so lazy

[@abdelrahman_alrawi]

thanks a lot

[@leusmaximusx]

thanks