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Ferroxyl Indicator

For an assignment we completed an assignment about rusting/corrosion. We did an experiment using ferroxyl indicator, which turns blue with the presence of Fe 2+ ions and pink in the presence of OH- ions. My question is: Why does the ferroxyl indicator turn pink in the presence of OH- ions and blue in Fe 2+ ions?

Gemma
- Plymouth, Devon, England
2002

There are Fe3+ ions in ferroxyl indicator that turn blue when they become Fe2+ ions (that is, when they gain an electron). The solution turns pink in the presence of OH- ions. This is because of, most usually, an electrochemical cell in which one metal or part of a metal is acting as the cathode and accepting electrons (blue) while the other metal or part of a metal is acting as an anode (pink). The colours indicate electron flow and a redox reaction

Stephanie Miller
- Brisbane, Qld, Australia
October 30, 2011