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# Equilibrium Constant Kc

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Why bother with a post grad course - waste of time? 17-10-2016
1. A mixture of 1 mole of ethanoic acid, 2 moles of ethanoic and 1 mole of water was allowed to reach EQM. On analysis, the EQM mixture was found to contain 0.257 mole of ethanoic acid. Find Kc for the reaction...CH3C00H+C2H5OH----><----CH3C00C2H5+ H20

Hi, the answer I'm getting is 1.313, my tutor says the answer is '4 something'. Where am I going wrong?
2. (Original post by Aclarke55)
A mixture of 1 mole of ethanoic acid, 2 moles of ethanoic and 1 mole of water was allowed to reach EQM. On analysis, the EQM mixture was found to contain 0.257 mole of ethanoic acid. Find Kc for the reaction...CH3C00H+C2H5OH----><----CH3C00C2H5+ H20

Hi, the answer I'm getting is 1.313, my tutor says the answer is '4 something'. Where am I going wrong?
I got 4.01

3. Here it is, sorry it's a mess.
4. (Original post by Aclarke55)
Here it is, sorry it's a mess.
Isn't the ratio one-to-one?
5. (Original post by Aclarke55)
Here it is, sorry it's a mess.
All equilibrium values ok except for ethanol. Why did you take 0.743 away twice and why did you square the ethanol term in the equilibrium equation?
6. (Original post by TeachChemistry)
All equilibrium values ok except for ethanol. Why did you take 0.743 away twice and why did you square the ethanol term in the equilibrium equation?
I thought because there was two moles that it had to be squared?
And took it away twice again because there was 2 moles.
Is that my issue?
7. (Original post by Aclarke55)
I thought because there was two moles that it had to be squared?
And took it away twice again because there was 2 moles.
Is that my issue?
Yes. The coefficients are 1 : 1 : 1 : 1 so no need for squares.
8. Thanks for your assistance :-)
9. Now I'm getting 6.78
10. My mate accidentally blew something up in a lesson
11. (Original post by The Blue Nose)
My mate accidentally blew something up in a lesson
Interesting anecdote.
12. Kc = [0.743][1.743]/[0.257][0.743]=6.78
13. (Original post by Aclarke55)
Kc = [0.743][1.743]/[0.257][0.743]=6.78
..
14. (Original post by EricPiphany)
..
Thank you!!! How daft of me.

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