What happens when two soluble salts are mixed?

• A. A gas is released
• B. An insoluble precipitate forms
• C. No reaction occurs
• D. Only heat is produced

Answer: (B)

When soluble salts dissolve, their ions are free in solution. A reaction occurs if those ions combine to form a salt that is not very soluble, so it comes out as a solid. That’s why you often see a solid precipitate form when two soluble salts are mixed—examples like mixing silver nitrate with sodium chloride gives solid silver chloride while the other product stays dissolved. If every possible product were soluble, nothing would appear to change. So the formation of an insoluble precipitate is the typical outcome described here.