27
About 2 years ago I purchased 2 liters of 98% concentrated sulfuric acid. It's in a standard poly bottle with leakproof lids, and originally was clear. Recently I noticed the acids have turned a dark gray; almost black color. They have both never been opened.
I suspect there was something in the lid that was eroded by the acid, but is there any other reason sulfuric acid would darken over time?
2026-10-22
