Okay, so apparently ASA and FeCl3 form a violet complex and FeCl3 forms with phenol groups to make purple. Looking at the structures of ASA and salicylic acid, only salicylic acid has the phenol group. The thing is, salicylic acid is supposed to be an impurity in the synthesized ASA.
If they both form purple, how am I supposed to look at two solutions and determine which one has the higher concentration of ASA in it?
To determine which solution has a higher concentration of ASA, you can use a spectrophotometer to measure the absorption of the violet complex formed when ASA reacts with FeCl3. The color intensity of the complex is directly proportional to the concentration of ASA in the solution. Follow these steps to compare the concentrations:
1. Prepare two solutions: one with a known concentration of ASA (reference solution) and the other containing the synthesized ASA solution (unknown solution) that you want to analyze.
2. Measure the absorption of the reference solution in the spectrophotometer at a specific wavelength that corresponds to the maximum absorbance of the violet complex of ASA with FeCl3.
3. Record the absorbance value of the reference solution.
4. Measure the absorption of the unknown solution using the same wavelength and same cuvette (a container for holding the solution) in the spectrophotometer.
5. Compare the absorbance value of the unknown solution with that of the reference solution. If the absorbance of the unknown solution is higher, it indicates a higher concentration of ASA. If it is lower, the concentration of ASA in the unknown solution is lower.
Remember to perform this experiment at the same temperature and using the same volume of solutions to ensure accurate results.