# What is the Chemical Reaction that Explains why Rubbing Ascorbic Acid on Rust Stains Removes Them?

I am a pool maintenance technician. In the industry, we pour bags of Vitamin C (ascorbic acid) into the pool to remove rust stains from the fiberglass surface. I am trying to determine the chemical equation behind this phenomenon as it works really well but was unable to find anything online. Any help would be appreciated.

• Jun 12 at 19:34
• @andselisk - I don't think this is just an acid reaction here. Ascorbic acid can also reduce Fe(III) to Fe(II), which is more soluble and can wash away. Jun 12 at 21:04
• And ascorbic acid also forms stable complexes with iron: amazon.com/Adapter-Desktop-ALINKVITE-Adapters-Wireless/dp/…, pubmed.ncbi.nlm.nih.gov/6514543 . This chelation of iron can be used to enhance its absorption in the body, pubmed.ncbi.nlm.nih.gov/15743017 Jun 13 at 1:21
• @Andrew I agree 100 %, that's why I dropped my dupe-close-vote and just left some links to related posts. Jun 14 at 5:42

Conceptually, it's something like $$\ce{\text{ascorbic acid} + 2Fe^3+ -> \text{dehydroascorbic acid} + 2Fe^2+ + 2H+}$$