Question

Two experiments were done. One, using an mL of an unknown solution + nmL iron (III)...

Two experiments were done. One, using an mL of an unknown solution + nmL iron (III) solution + aspirin. The other, NaOH, mL iron (III), and acetyl salicylic acid. Explain why the solutions have a purple color after the iron reagent is added. Yes, the answer is because it is absorbing the other colors, but what is absorbing the other colors?

These tubes were put through the spectrophotometer after all substances had been added. Explain why the spectrophotometer is 'blanked' with JUST the iron reagent. Why couldn't deionized water be used?

Homework Answers

Answer #1

Fe(III) forms a chelate complex with salicylic acid which has purple color. therefore, when a solution is made either with salicylic acid or with aspirin having trae amount of salicylic acid in it, we see color formation in solution due to the resulting complex formed.

The Fe(III) itself absorbs some light and gives an absorbance value for the solution. Therefore, it is necessary to blank the spectrophotometer with a Fe(III) solution prior to measurement of test solutions.

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