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You are watching: Why would a percent yield be more than 100


I am looking for a general answer; nothing too thorough. And no. This is not a homejob-related question. It taken place to me in lab and also I am wondering what error I might have committed.


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Preface: The problem is that you have actually overdeclared your percent yield, and the symptom is that it is over 100%.

Example: You and also your friend each do an experiment wright here the literature claims the yield should be ~65%. You both use poor strategy and fail to dry your product, causing you to attribute water mass as product mass. Your friend"s yield is 101%, and yours is 99%. Both you and also your frifinish are wrong, for the very same reason! Don"t make the mistake of avoiding your analysis when percentage yield drops below 100%. Don"t chastise your friend for having an "impossible" yield while patting yourself on the earlier for your "99%"!

Overstatement of portion yield happens for the complying with reasons:

Zero) Your model of the reaction muzic-ivan.info is simply wrong. Unmost likely in an undergraduate establishing, however worth discussing.

1) Your math is wrong. Worth double checking and straightforward to preeminence out as a resource of error.

2) You supplied even more reactant than you believed. Most errors in reactant measurement cause you to use much less reactant than tape-recorded (e.g. deliver errors, impure reactants), but you can maybe have supplied even more than you thought. Beyond basic measurement errors, probably your limiting reagent was offered to you in solution, and also that solution was of better concentration than reported. Put a little of time into reasoning around this, however protocols normally minimize the possibility of this kind of error.

3) You actually have actually much less product than you think.

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This is the most likely culprit. You have to be really hocolony through yourself here. In most experiments, you take the mass of something at the end, and speak to it the mass of your product. Is it really your product? Or does that mass contain impurities which reason you to misreexisting impurities as product. Likely culprits are solvents (e.g. water from improper drying), side-products, and/or unreacted reagent. Have you really done your best to filter and also rerelocate them? If not, your yield will certainly be inflated.