# What type of reaction occurs when one compound reacts and is broken down into different elements or simpler compounds?

Feb 9, 2017

#### Explanation:

When a binary compound breaks down into separate elements OR when compounds break down into simpler compounds, it is known as a decomposition reaction.

The general formula for decomposition reactions are: $A B \to A + B$

Binary compounds:

$H g O \left(s\right) \to H g \left(l\right) + {O}_{\text{2}} \left(s\right)$

$2 {H}_{\text{2"O (l) -> 2H_"2" (s) + O_"2}} \left(s\right)$

$2 N a C l \left(s\right) \to 2 N a \left(s\right) + C {l}_{\text{2}} \left(g\right)$

Simple compounds:

When a metal carbonate breaks down, it yields a metal oxide and carbon dioxide.

$C a C {O}_{\text{3" (s) -> CaO (s) + CO_"2}} \left(g\right)$

When a metal hydroxide breaks down, it yields a metal oxide and water. Acids work the same way, but no formation of a metal compound.

$M g {\left(O H\right)}_{\text{2" (aq) -> MgO (s) + H_"2}} O \left(l\right)$

${H}_{\text{3"PO_"4" (aq) -> P_"2"O_"5" (s) + H_"2}} O \left(l\right)$

When a chlorate breaks down, it yields a binary salt and oxygen gas.

$K C l {O}_{\text{3" (s) -> KCl (s) + O_"2}} \left(g\right)$

Hope this helps :)