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Author Topic: Crono's Brainiac Contest (PREVIOUSLY CONTENST)! Question 1  (Read 2161 times)

Offline Crono0001

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Crono's Brainiac Contest (PREVIOUSLY CONTENST)! Question 1
« on: April 05, 2011, 09:31:44 PM »
So I was thinking of posting a question from one of my homework assignments to help exercise the brains of this community every so often (probably as soon as someone solves the question).  The first person to successfully post the answer gets a mystery prize (and it'll be something tangible, not internet cookies).  Most of my questions will be chemical engineering related, but not always.  The winner will be announced, as well as the prize, as soon as I receive the correct answer.  Serious contestants only.  Do note you will also be competing against members at TucsonAirsoftCoalition.

So let's start off:


Difficulty: 1/10

CHEMICAL ENGINEERING: Chemical Equilibrium
--------------------------------------------------------------
For the following gas phase reaction in equilibrium at 500 K, it is found that A is 10% dissociated at 10 atm pressure:

A(g) = B(g) + C(g)

Where A, B, and C are all vapors.  Assume ideal gas behavior and calculate the percent dissociation of A at 440.6 degrees F and 760 torr.
« Last Edit: April 07, 2011, 08:32:05 PM by Crono0001 »
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Offline Crono0001

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Re: Crono's Brainiac Contenst! Question 1
« Reply #1 on: April 05, 2011, 10:16:16 PM »
EDIT:
Okay, instead of getting my inbox spammed with tons of wrong answers, how about we have people start posting what you think is the answer.  I'll give feedback accordingly.
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Offline axisofoil

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Re: Crono's Brainiac Contenst! Question 1
« Reply #2 on: April 05, 2011, 10:37:02 PM »
7? btw, I've given in to the "I really dgaf, but I'll post a random number just in case" feeling on life tonight.
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Offline Crono0001

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Re: Crono's Brainiac Contenst! Question 1
« Reply #3 on: April 05, 2011, 11:54:38 PM »
Quote from: "axisofoil"
7? btw, I've given in to the "I really dgaf, but I'll post a random number just in case" feeling on life tonight.

No, sorry.
HINT: The disassociation percent will be a percentage
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Offline Shadow

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Re: Crono's Brainiac Contenst! Question 1
« Reply #4 on: April 06, 2011, 11:39:29 AM »
42... and bring your towel!
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Offline axisofoil

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Re: Crono's Brainiac Contenst! Question 1
« Reply #5 on: April 06, 2011, 02:43:28 PM »
Quote from: "Crono0001"
Quote from: "axisofoil"
7? btw, I've given in to the "I really dgaf, but I'll post a random number just in case" feeling on life tonight.

No, sorry.
HINT: The disassociation percent will be a percentage

You asked for a percentage. I gave you a number. It is easily inferred that my number (7, in this case), refers to that many percentage points, i.e. 7%. I suppose if you were a pure mathematician, you could also assume I meant the number 7, which would correspond to 700%. Either way, the number would be easily interpreted as an erroneous answer...
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Offline Crono0001

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Re: Crono's Brainiac Contenst! Question 1
« Reply #6 on: April 06, 2011, 04:15:24 PM »
Quote from: "derekr44"
42... and bring your towel!

Sorry.  As stated earlier, the answer will be a percentile (or, numerically, less than zero).

By the way, the prize will include me shipping something to you, or something along those lines...  if that helps motivates any of you.
Some helpful things to look up would be chemical equilibria pertaining to reactions.
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Offline DMAN007

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Re: Crono's Brainiac Contenst! Question 1
« Reply #7 on: April 06, 2011, 04:34:06 PM »
52%?
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Offline Schwer_Punkt_91

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Re: Crono's Brainiac Contenst! Question 1
« Reply #8 on: April 06, 2011, 08:12:26 PM »
30.3%
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Offline Crono0001

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Re: Crono's Brainiac Contenst! Question 1
« Reply #9 on: April 06, 2011, 10:03:29 PM »
Quote from: "Schwer_Punkt_91"
30.3%

Very nice.  The answer indeed, is 30.28%

Winner: Schwer_Punkt_91
Prize: $10.00 gifted via PayPal

In order to do this problem, one must calculate the extent of reaction (here we'll call it X).

Assume we begin with 1 mol of A.  At a ten percentage disassociation, X=.1, and thus you'll have .9 mols of A left afterwards, with .1 mols of each B and C.  Chemically, it takes 1 mol of A to create 1 mol of B and 1 mol of C.  So if only .1 mols of A react, you get .1 mols of B and .1 mols of C.  Using this information, we can go ahead and solve for our Keq (or equilibrium constant).

Keq = [A]/([C]) * Pt where Pt is the total pressure, and [A] is the mol fraction of A, etc.
[A] = 1-X/1.1    = X/1.1     [C]=X/1.1
The concentrations of each species is taken by the amount of moles of that species divided by the total.
Because the equilibrium constant is not a strong function of pressure, we can replace Pt with our new pressure and solve for our new X, which happens to be .3028, or 30.3%

I'll try to get a new question up soon.
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Offline Vince

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Re: Crono's Brainiac Contenst! Question 1
« Reply #10 on: April 07, 2011, 07:19:48 PM »
Am I the only person who noticed that this contest about being smart has a typo in the title?
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Offline kman94

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Re: Crono's Brainiac Contenst! Question 1
« Reply #11 on: April 07, 2011, 07:50:08 PM »
Quote from: "Vince"
Am I the only person who noticed that this contest about being smart has a typo in the title?
Lol. Maybe its a differant word he is trying to convey?
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Offline Crono0001

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Re: Crono's Brainiac Contenst! Question 1
« Reply #12 on: April 07, 2011, 08:31:12 PM »
Quote from: "Vince"
Am I the only person who noticed that this contest about being smart has a typo in the title?

I sure as hell didn't notice.
English is my second language :'(
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Offline kman94

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Re: Crono's Brainiac Contest (PREVIOUSLY CONTENST)! Questio
« Reply #13 on: April 07, 2011, 08:40:00 PM »
I know this is getting a little off topic, but is it really your second language? What's your first?
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Offline Crono0001

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Re: Crono's Brainiac Contest (PREVIOUSLY CONTENST)! Questio
« Reply #14 on: April 07, 2011, 08:42:44 PM »
Quote from: "kman94"
I know this is getting a little off topic, but is it really your second language? What's your first?

Cantonese,
Doesn't really count though.  I went to school here since I was a kid, so you could say English is also a primary language.  I was frantically trying to defend myself :P
second question up by the way:  viewtopic.php?f=23&t=30128&p=229918#p229918, please lock this thread
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