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What is a real world situation in which a double replacement reaction occurs?

And I don't mean something like "one guy's hat is switched with another guy's hat" or "two guys switch girlfriends," or something like that. I mean an actual chemical example of it occuring in daily life.

Public Comments

1. The pancreas secretes sodium bicarbonate into the small intestine to neutralize gastric acid. The same thing happens when you have acidity and eat Tums. HCl + NaHCO3 → NaCl + H2CO3 Basically, any acid-base reaction is a metathesis reaction.