Chromium diphenylcarbazide comlex?

04 January 2023 0 3K Report

May I ask a question.. I did calibration curve for chrome using concentrations of 20, 40, 60, 80, and 100 mg/l of chromium.

After that I added diphenylcarbazide and phosphoric acid on chrome solution and it gave me purple color.

When I was measuring it on the spectrophotometer

I noticed that the color of the two flasks that have a concentration of 80 and 100 mg/l disappeared after ten minutes.

can I know why?

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