# What are the products of a double displacement reaction?

Nov 24, 2015

One of the products must be a solid precipitate, an insoluble gas, or water.

#### Explanation:

A double displacement (double replacement) reaction occurs when two aqueous ionic solutions react to produce a solid precipitate, an insoluble gas, or water. If none of these are produced, then a double displacement did not take place.

The general equation for a double displacement reaction is $\text{AX + BY}$$\rightarrow$$\text{AY + BX}$, where $\text{A}$ and $\text{B}$ are cations, and $\text{X}$ and $\text{Y}$ are anions.

Examples of double displacement reactions.

$\text{BaCl"_2("aq")" + MgSO"_4("aq")}$$\rightarrow$$\text{BaSO"_4("s")darr"+ MgCl"_2("aq")}$

$\text{Na"_2"S(aq)" + "2HCl(aq)}$$\rightarrow$$\text{H"_2"S(g)"uarr"+ 2NaCl(aq)}$

$\text{HCl(aq)" + "NaOH(aq)}$$\rightarrow$$\text{NaCl(aq)" + "H"_2"O(l)}$

The down arrow $\downarrow$ indicates the formation of a solid precipitate, and the up arrow $\uparrow$ indicates the formation of a gas. You can also use the symbols $\left(\text{s}\right)$ and $\left(\text{g}\right)$.