Consider the following solubility of caffeine listed in molarity for various sol
ID: 868170 • Letter: C
Question
Consider the following solubility of caffeine listed in molarity for various solvents.
Solubility:
Acetone
0.061M (room temperature) 0.094M (hot acetone)
Ethanol
0.029M (room temperature) 0.042M (hot ethanol)
Ethyl
0.041M (room temperature) 0.069M (hot ethyl acetate)
Acetate Water
0.104M (room temperature) 0.136M (hot water)
(a) Which one of the solvents listed above is a good single crystallization solvent for caffeine?
(b) Which pair of solvents listed above is a good mixed crystallization solvent for caffeine?
Explanation / Answer
(a) Acetone is a good solvent for crystallization as the difference in solubility between hot and room temperature is highest for acetone, equal to 0.033M.
(b)
Solvent pair will have one solvent highest solubility in cold water and otherwith lowest solubility in hot water. This is satisfied by acetate water with (highest 0.104M at room temperature) and ethanol ( lowest 0.042M hot).