% Yield

[Jeremy Feng 1A]

When performing an experiment in the lab, is there a cutoff for acceptable % yield? What is considered "efficient"?

[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.

[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.

[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.

[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.

[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.

[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.

[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%)

[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.