In organic chemistry labs, acid base extraction is a convenient way to separate components of a mixture. It relies on the principle that an organic acid or base generally becomes more water-soluble when you neutralize it to make a salt. Once you perform an extraction of this kind, you need to calculate a percent recovery to determine precisely how well you did. The data you need are the starting amount of each kind of compound present and the final amount you recovered.
Estimate how much of each compound was present originally. If you started with a sample composed roughly of one-third neutral compound, one-third organic base and one-third organic acid, you can take the starting sample mass and multiply it by 1/3 to get the starting mass of each. For example, if you started with 1 gram of material, multiply by 1/3 to get 1/3 gram of neutral compound, 1/3 gram of organic base and so forth.
Divide the final amount of each type of compound by the starting amount. If you ended up with 1/10 gram of organic base, for example, and you started with 1/3 gram, you would divide 1/10 by 1/3 to get 3/10.
Multiply your answer from the last step by 100 to convert it into a percent format. To continue the same example, 0.3 x 100 = 30 percent.
Note that your percent recovery may be different for each type of compound. That's entirely normal, because an acid-base extraction is a multistep process. So depending on how careful you were with each step, you might have a better percent recovery for some of the compounds in the mixture than for others.
- "Techniques in Organic Chemistry"; Jerry R. Mohrig, et al.; 2010
- Penn State Chemistry: Liquid/Liquid Extraction
- Photo Credit Hemera Technologies/AbleStock.com/Getty Images