Your stomach acid is strong enough to dissolve a razor blade — slowly
Stomach acid (hydrochloric acid) has a pH of around 1.5–3.5 — roughly equivalent to battery acid. Given enough time, it can dissolve metals including iron. A razor blade left in stomach acid would gradually corrode over several days. Your stomach lining is protected by a mucus layer 1–1.5 mm thick that renews itself every 3 days, preventing the acid from eating through the organ itself. When this mucus layer fails partially, the result is a stomach ulcer.
We contain something with the chemical strength of battery acid, held at bay by a thin layer of mucus that replaces itself every three days. The body's margin for error here is remarkably thin.
“Your stomach acid is pH 1.5 — strong enough to slowly dissolve a razor blade. A thin mucus layer (replaced every 3 days) is all that stops it from eating through your stomach wall. ⚗️ #OddlyHuman”