TYPES OF INORGANIC CHEMICAL REACTIONS

Elements and compounds react witheach other in numerous ways. Almost every inorganic chemical reaction falls into one or more of four broad categories.

I. Combination Reactions

Two or more reactants formone productin a combination reaction. An example of a combination reaction is the formation of sulfur dioxidewhen sulfur is burned in air:

S (s) + O₂ (g) --> SO₂ (g)

II. Decomposition Reactions

In a decomposition reaction, a compound breaks downinto two or more substances.

Decomposition usually results from electrolysisor heating. An example of a decomposition reaction is the breakdownof mercury (II) oxideinto its component elements:

2HgO (s) + heat --> 2Hg (l) + O₂ (g)

III. Single Displacement Reactions

A single displacement reaction is characterized by an atom or ion of a single compound replacingan atom of another element. An example of a single displacement reaction is the displacement of copper ions in a copper sulfate solutionby zinc metal, forming zinc sulfate:

Zn (s) + CuSO₄ (aq) --> Cu (s) + ZnSO₄ (aq)

Single displacement reactions are often subdivided into more specific categories, e.g., redox reactions- chemical reactions which involve oxidation and reduction.

IV. Double Displacement Reactions

Double displacement reactions also may be called metathesis reactions. In this type of reaction, elements from two compounds displace each other to form new compounds. An example of a double displacement reaction occurs when solutions of calcium chlorideand silver nitratereact to form insoluble silver chloridein a solution of calcium nitrate.

CaCl₂ (aq) + 2 AgNO₃ (aq) --> Ca(NO₃)₂ (aq) + 2 AgCl (s)

A neutralization reactionis a specific type of double displacement reaction that occurs when an acidreacts with a base, producing a solution of salt and water. An example of a neutralization reaction is the reaction of hydrochloric acidand sodium hydroxideto form sodium chlorideand water:

HCl (aq) + NaOH (aq) --> NaCl (aq) + H₂O (l)

Remember that reactions can belong to more than one category. Also, it would be possible to present more specific categories, such as combustion reactionsor precipitation reactions.