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Topic: Chemical Engineering or Chemistry  (Read 26292 times)

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Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #15 on: January 09, 2008, 05:13:13 PM »
It was a fluke...some very esoteric unit substitution....set the entire answer to right!!!!

If you ever take E&M....LOL  in my class 3 exams..all take home 5 questions each...3 weeks to do the exam....

You will do just fine...take it a step at a time...
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Offline bball927je

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Re: Chemical Engineering or Chemistry
« Reply #16 on: January 10, 2008, 10:56:29 PM »
A 2.000g sample of CoCl2*xH2O is dried in an oven. When the anhydrous salt is removed from the over, its mass is 1.565g. What is the value of x?

That is the only problem I got wrong on a chemistry competition test.. I guess it is because I was absent the day we learned it. I know this is the wrong topic but I figured since I already started this topic I might as well post this in here.
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"We can't solve problems by using the same kind of thinking we used when we created them."-Albert Einstein

Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #17 on: January 10, 2008, 11:06:12 PM »
you are trying to determine the formula of your hydrate by mass difference....

OK so you have 2.000 g of this material with unknown formula (at the moment) because it has not yet been dried..

You are drying it to determine the formual by weight difference,

So you have 2,000 g and your final mass after drying is 1.565 g....the difference in the two values is the amount of water lost to drying in grams...

2.000 g - 1.565 g = 0.435 g

0.435 g is the mass of the water lost to drying

Can you figure out what to do next??
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Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #18 on: January 10, 2008, 11:17:32 PM »
You are determining the empirical formula for the hydrated salt.  You do this using theinitial mass (weight) and the final mass (weight) after drying...
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Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #19 on: January 10, 2008, 11:42:41 PM »
1. Determine the mass of water driven from the hydrate during the heating process. = 0.4350 g

2. Determine the mass of anhydrous salt left in the crucible after the heating process. = 1.565 g

3. Determine the percentage of water in the hydrate. Use parts/total parts x 100
(0.4350 g/2.000 g )x 100 = 21.75% ( 4 significant digits allowed)


4. Determine percentage of anhydrous salt left behind.   Use parts/total parts x 100
(1.565 g / 2.000 g) x 100 = 78.25% ( 4 significant digits allowed)

5. Determine mols of anydrous salt present in hydrate.  Mass of the anhydrous salt is mass of CoCl2 =  129.83 g/mol Then (1.565 g  / 129.83 g/mol) = 0.01205

6. Determine mols of water present in hydrate.  Mass of water is mass H2) = 18.01 g/mol
(0.4350 g / 18.01 g/mol) = 0.02415

7. Determine the mole ratio  of water to salt:  Use ratios to determine this with any luck get a whole number ratio...

(0.01205/0.01205 )= 1   and then (0.02415/0.01205) = 2.00

The mol ratio of water to salt 2.00  to 1 (2 to 1)

Formula :  CoCl2 x 2H2O

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Offline Mitch

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Re: Chemical Engineering or Chemistry
« Reply #20 on: January 11, 2008, 12:49:27 AM »
As a scientist, problems due have a way of prickling at you. I've been thinking of a way to make cylooctatriene from cyclooctadiene for the past week now and it is really hard to focus with this auxiliary research problem in the back of my mind. I've scheduled tomorrow to hammer it out.
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Offline bball927je

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Re: Chemical Engineering or Chemistry
« Reply #21 on: January 11, 2008, 06:17:08 AM »
Ughhhhhh.... that problem was so easy... i really should have gotten it and tied for first in my competition instead of second..
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Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #22 on: January 11, 2008, 08:06:01 AM »
Well..

Look, my friend AVM used to participate in Math Competitions...and if you were sick the day that problem was presented...OK so you did not learn the method for solving it quickly...they always give you a trick for solving quickly...so you missed one problem...YOU PLACED RIGHT!!!!

And I am sure there were so many who did not....

And that is alot more than someone who did not...my guess is you probably would have done it more quickly than I did above if you had made the review that day....

Hang in there...beieve me there will be another competition and another chance at First Place...

Congratulations on Second Place!!!!
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Offline bball927je

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Re: Chemical Engineering or Chemistry
« Reply #23 on: January 11, 2008, 08:42:59 AM »
Thanks for the congratulations and the explanation. At least now I will know how to do it for the next competition if it comes up.
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"We can't solve problems by using the same kind of thinking we used when we created them."-Albert Einstein

Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #24 on: January 11, 2008, 08:51:07 AM »
And see how it is....did you read Mitch's comment...it BOTHERS YOU when something is not solved...it naggs at your brain cells....you cannot rest until it is finished.....do you see the point???

That would be common to both scientists and engineers...it bugs you when something is not resolved/solved....

Do NOT minimize your accomplishments/achievements...instead see second place as a launching zone to gt to first...YOU DID GOOD!!!!!
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Offline IITian

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Re: Chemical Engineering or Chemistry
« Reply #25 on: January 11, 2008, 11:05:20 AM »
I did a BS in Chemistry and then moved on to do Post-BS degree in Chemical Technology. I think doing both gives an extra edge! You can understand the scientific basis of the processes as well as the Engineering aspects of it  :)
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Offline bball927je

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Re: Chemical Engineering or Chemistry
« Reply #26 on: January 11, 2008, 12:06:10 PM »
How long did it take you to finish accomplishing all that? And was it very challenging to do?
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"We can't solve problems by using the same kind of thinking we used when we created them."-Albert Einstein

Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #27 on: January 11, 2008, 12:08:52 PM »
IITian has made an excellent point about being well-rounded and diverse.

I can tell you that diversity is a prime point companies seek in a resume.  I have to say my friend DB who has the BS in Chemistry and MS in Envirnmental Engineering...WOW she sure rakes in the bucks..and her job is interesting...she travels...she presents papers, she works on integrated projects with scientists and engineers...BEST OF BOTH WORLDS...



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Offline bball927je

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Re: Chemical Engineering or Chemistry
« Reply #28 on: January 11, 2008, 12:12:31 PM »
Lol you seem to have a lot of interesting friends with great jobs in chemistry..
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"We can't solve problems by using the same kind of thinking we used when we created them."-Albert Einstein

Offline Alpha-Omega

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Re: Chemical Engineering or Chemistry
« Reply #29 on: January 11, 2008, 12:17:53 PM »
I sure do....they all do different thingsa...aey have tried to remain diverse.

AVM :is a Field Technical Specialist-IC
DB:  is in R&D with Chicago Metropolitan Water District
RLW:  Well Fermi, Argonne, University of Wisconsin
AC Jr:  Dual Degreed Nuclear Engineer/Computer Engineer
AM:  R&D Pfizer
PMH:  Manager QA/QC MGP

Now I am pushing for XRF Applications...with any luck....
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