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 would want to use a basic aqueous solution. Caffeine is a weakly basic compound, meaning it will exist primarily in its neutral form at low pH levels and will become more soluble in water at higher pH levels. A basic solution will help increase the solubility of caffeine in water and aid in its extraction.
Looking at the given options, the only solution that is basic is option A with a pH greater than 14, using 2.5 M NaOH (aq). NaOH is a strong base, and when dissolved in water, it will dissociate into hydroxide ions (OH-) and sodium ions (Na+). This high concentration of hydroxide ions will increase the pH of the solution and make it highly basic.
Therefore, option A with a pH greater than 14, using 2.5 M NaOH (aq), would be the appropriate choice for extracting caffeine.