Question

What does the formation of a precipitate indicate?

Answer 1

Well, it indicates that a chemical reaction has taken place.

Explanation:

And we can illustrate the formation of a precipitate by a stoichiometrically balanced equation:

`AgNO_3(aq) + NaCl(aq) rarr AgCl(s)darr + NaNO_3(aq)`

And because the nitrate and sodium ions are along for the ride, we could write a net ionic equation:

`Ag^(+) + Cl^(-) rarr AgCl(s)darr`

Bonds are broken, and bonds are formed in a new substance, and thus chemical change has manifestly occurred.