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Author Topic: Percent yield...over 100%???  (Read 25459 times)

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prncess23

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Percent yield...over 100%???
« on: May 09, 2009, 10:12:45 PM »

hi guys,

i calculated my % yield for the Synthesis of m-Aminoacetophenone from m-Nitroacetophenone lab and i got a value over 100%.?

1.053 g NitroAc (1 mol NitroAc/165.15 g NitroAc)(1 mol AminoAc/1 mol NAc) (135.16 g AminoAc/1 mol AminoAc)=0.8618g

% yield= 1.244g/0.8618 (100%)=144.3%


my data is below...


m-Nitroacetophenone    1.053 g
Granular Tin metal   1.239 g
m-Aminoacetophenone (product)   1.244 g
Melting point   97.5°C
Percent Yield   144.3%
Literature value   96°C - 98°C
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sjb

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Re: Percent yield...over 100%???
« Reply #1 on: May 09, 2009, 10:35:02 PM »

I know you seem to have a sharp melting point (which is good), but what other analysis techniques do you know / have you used to confirm the purity of your product?
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prncess23

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Re: Percent yield...over 100%???
« Reply #2 on: May 09, 2009, 10:37:55 PM »

i have an IR which i am analyzing right now. it looks good...the numbers dont seem right though.

i knwo some reactions you get a very high % yield...but i dont think this is one of them...it should be under 100% right?
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Arkcon

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Re: Percent yield...over 100%???
« Reply #3 on: May 10, 2009, 03:40:37 AM »

By the law of conservation of matter, yes, there is an error somewhere.  A big one like this, is not likely based of an error in purity.  Or at least, not completely. Maybe one of your volume or weighings is in error?  See if you can review your lab notes, and your memory of what you did, to try and see what might be the problem.
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StarvinMarvin

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Re: Percent yield...over 100%???
« Reply #4 on: May 10, 2009, 07:34:25 AM »

How did the workup look like? From the looks of it, you could have some solvent in it or the tin metal which was not removed completely.
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408

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Re: Percent yield...over 100%???
« Reply #5 on: May 17, 2009, 01:37:12 PM »

Post the procedure if you want better answers.  But gut feeling: wet product
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soutoh65

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Re: Percent yield...over 100%???
« Reply #6 on: May 18, 2009, 05:15:22 PM »

impossible the yield would not be > 100 percent and at best approach the 99th percentiles.

one of several things have occurred
1. contaminant of purity
2. weight error
3. or substrate failure
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