Determination of salicylates using the occurrence of violet color in the solution
name: Applying a qualitative reaction of salicylates and iron (III) ions
The Home Scientist 023 - Salicylate determination with visual colorimetry, Part I
What would happen? Aspirin/Salicylic Acid is treated with Ferric Chloride!
by Terry Patamawenu
Wear eye protection and lab gloves.
Always follow general safety
recommendations. Please note that conducting chemistry
experiments you must comply with the relevant legal procedures in
C7H4O3 2-+ [Fe(H2O)6]3+ → [(C7H4O3)Fe(H2O)4]+ + 2H2O
- Prepare 0.1% solution of iron (III) chloride in water.
- Prepare a set of salicylic acid water solutions of various concentrations and pour these solutions into test-tubes.
- Prepare a water solution of aspirin in a test-tube.
- Add about 1 ml of the iron (III) chloride solution into each test-tube. Fix color change of solutions.
Iron (III) ions form a blue-violet complex with salicylate dianions, and the intensity of the color depends on the concentration of salicylate dianions. With acetylsalicylic acid (aspirin) a pale pink complex with iron (III) is formed. These two reactions are used for detecting salicylate presence and determining the purity of aspirin.