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

1 Answer
Feb 9, 2017


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: #AB -> A+B#

Binary compounds:

#HgO(s) -> Hg(l)+O_"2"(s)#

#2H_"2"O (l) -> 2H_"2" (s) + O_"2" (s)#

#2NaCl (s) -> 2Na (s) + Cl_"2" (g)#

Simple compounds:

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

#CaCO_"3" (s) -> CaO (s) + CO_"2" (g)#

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.

#Mg(OH)_"2" (aq) -> MgO (s) + H_"2"O (l)#

#H_"3"PO_"4" (aq) -> P_"2"O_"5" (s) + H_"2"O (l)#

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

#KClO_"3" (s) -> KCl (s) + O_"2" (g)#

Hope this helps :)