What should be the pH of the aqueous layer to extract caffeine? There are three aqueous solutions that you may choose from.
Answer
A.
pH >14, using 2.5 M NaOH (aq)
B.
pH 1, using 0.1 M HCl (aq)
C.
pH 6.2, using 0.1 M NaHCO3 (aq)
To extract caffeine, you need to consider the solubility of caffeine in different pH conditions. Caffeine is a weak base, so it will be more soluble in an acidic solution and less soluble in a basic solution.
Option A: pH >14, using 2.5 M NaOH (aq)
In this case, the solution is highly basic. Since caffeine is less soluble in a basic solution, it is not a suitable choice for extracting caffeine.
Option B: pH 1, using 0.1 M HCl (aq)
This solution is highly acidic. Caffeine is more soluble in acidic solutions, so this option is a viable choice for extracting caffeine.
Option C: pH 6.2, using 0.1 M NaHCO3 (aq)
This solution is slightly acidic. Although caffeine is more soluble in acidic solutions, a pH of 6.2 might not be sufficiently acidic to maximize the extraction of caffeine. However, since it is not a highly basic solution, it may still extract some caffeine.
Therefore, option B with pH 1, using 0.1 M HCl (aq), is the most suitable choice for extracting caffeine.