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% Yield

Posted: Thu Oct 04, 2018 11:24 pm
by Jeremy Feng 1A
When performing an experiment in the lab, is there a cutoff for acceptable % yield? What is considered "efficient"?

Re: % Yield

Posted: Thu Oct 04, 2018 11:30 pm
by maldonadojs
From my experience I have been told it is based off of the experiment, for some are notorious for having low % yield and some high. It depends because some experiments' procedures have more impurities or are more difficult and require more intense care. A short answer is no due to every experiment being different.

Re: % Yield

Posted: Fri Oct 05, 2018 9:38 am
by Manu Vohra 1L
There is no set cutoff. Multiple factors come into play when deciding whether a reaction is 'efficient' or not including the time needed for the reaction to occur, the cost of the materials involved, and the percent yield. Therefore, every reaction's efficiency will have to be gauged individually.

Re: % Yield

Posted: Fri Oct 05, 2018 10:05 am
by Kelly Zhang 1L
From what I learned in AP chem, there is no "acceptable" percent yield. When it asks for percent yield, its simply asking for you to calculate how much is produced vs the theoretical. The problems will typically ask what is the percent yield and will not ask you to interpret the percent yield. The percent yield depends on the individual experiment being conducted and the amount of reactants used.

Re: % Yield

Posted: Fri Oct 05, 2018 10:30 am
by Aakash Tammana 3H
The question doesn't really make sense - for example, if you were dealing with an experiment that, in a best case scenario, would yield a microscopic amount of product, it's still an acceptable % yield.

Re: % Yield

Posted: Fri Oct 05, 2018 1:06 pm
by Niveda_B_3I
There's no such thing as an unacceptable % yield. % yield is simply the comparison of the actual yield to the theoretical yield.

Re: % Yield

Posted: Fri Oct 05, 2018 4:08 pm
by Aria Soeprono 2F
I think you may be slightly confusing percent yield with percent error, in which case percent error is usually "acceptable" at around 5% (but it varies depending on the lab). In contrast, percent yield, although it may be affected by certain lab errors, does not directly correlate to error and has more to do with the actual product vs. theoretical. Therefore, as others have said, there is really no such thing as "acceptable" or not in terms of percent yield.

Re: % Yield

Posted: Wed Oct 10, 2018 9:09 pm
by Mallory_Podosin_1H
I don't exactly think that there is a "cutoff" in the lab unless you decided to create your own cutoff for a certain situation?
Percent yield is (actual yield/theoretical yield) *100%
Actual yield is always going to be less than theoretical yield - so the answer will always be 100% or less (I doubt it would ever be 100%)

Re: % Yield

Posted: Fri Oct 12, 2018 11:32 am
by Chem_Mod
Replies above are correct in that there is no general "acceptable cutoff" for yield, and that good yields vary given the reaction conditions. However, to give a number, generally in published papers in chemistry, people consider ~70% to be a decent yield for a reaction.