Causes for deviating yields

It is quite common in laboratory experiments to obtain a result that deviates from what you expected. It is important to accept that your result is what it is, and never try to amend the results to make it better. Rather, try to find reasons for the deviations. Here are some common examples:

The yield is lower than the expected yield. It could be that:

• You lost some product in transferring from one container to another.
• One of your reagents were diluted or contained an impurity, so you didn’t add as many moles as you thought you did.
• The reaction was not complete when you isolated the product.
• Some byproducts were formed.
• Some degradation of your reactants or products has occurred.
• You made an error somewhere in your calculation of moles and masses.

The yield is higher than 100 %. It could be that:

• Your product still contains some solvent (not completely dry).
• You forgot to tare the container before putting your product in there.
• You made an error somewhere in your calculation of moles and masses.