# What is an insoluble solid that forms as the result of a double-displacement reaction called?

Dec 5, 2015

It is called a precipitate because it "falls out" of solution, like precipitation such as rain falls out of the sky.

#### Explanation:

A double displacement (double replacement) reactions takes place when two aqueous ionic solutions react. One of the products must be a precipitate, an insoluble gas, or water.

The general form for a double displacement reaction in which a precipitate forms, also called a precipitation reaction or salt metasthesis, is as follows: $\text{AX"+"BY}$$\rightarrow$$\text{AY"+"BX}$, where $\text{A and B}$ are cations and $\text{X and Y}$ are anions.

Example of a precipitation reaction or salt metastasis.

$\text{AgNO"_3("aq")" + NaCl(aq)}$$\rightarrow$$\text{NaNO"_3("aq")" + AgCl(s)}$

$\text{AgNO"_3("aq")" + NaCl(aq)}$$\rightarrow$$\text{NaNO"_3("aq")" + AgCl} \downarrow$

You can use the symbol $\left(\text{s}\right)$ or $\downarrow$ to represent the precipitate.