Andreas von Einsiedel/Alamy
I have a stainless steel kitchen sink. When I clean it with bleach, leaving it instantly gleaming, what happens to the particles that were staining it?
Mark Dirnhuber
Bristol, UK
Stainless steel has chromium as the key ingredient: on contact with air (or even nitric acid) this forms a thin but resistant surface layer of chromium(III) oxide (Cr2O3), which protects the steel from further corrosion. This oxide layer may well pick up stains, for example from tannins, which are polyphenols from tea.
Bleach is sodium hypochlorite (NaOCl) and is a strong oxidising agent, which is alkaline…
