Question

In order to extract isobutyric acid from a solution of diethyl ether, one should wash the solution with:

• A. one $30mL$ wash of water
• B. three $10mL$ washes of water
• C. one $30mL$ wash of hexane
• D. three $10mL$ washes of hexane

Answer 1

The correct option is B three $10mL$ washes of water

lsobutyric acid has a carboxylic acid group, which is polar and can readily hydrogen bond. It can be extracted from the organic solvent diethyl ether by washing with a polar solution like water. Multiple small volume washes extract better than one large volume wash. Use of a second organic solvent, hexane, will not extract the isobutyric acid from the diethyl ether.
A. One $30mL$ wash of water is incorrect. Multiple smaller volume washes will yield higher extraction results.
B. Three $10mL$ washes of water is correct. Isobutyric acid will enter the aqueous layer and wash off of the organic layer of diethyl ether.
C. One $30mL$ wash of hexane is incorrect. Hexane is another organic solvent like diethyl ether.
D. Three $10mL$ washes of hexane is incorrect as explained above.