Inorganic Chemical Reactions can be categorized into the following broad categories: combination reactions, decomposition reactions, single displacement reactions and double displacement reactions.
a) Combination reactions are reactions where two or more reactants react together to form a fewer number of products. Consider the following reaction:
2H2 + O2 --> 2H2O
In the above reaction two hydrogen molecules are reacting with one oxygen molecule to form two molecules of water. Essentially, 3 molecules of the reactant are combining to form 2 molecules of the product - so a combination reaction must have occurred.
b) Decomposition reactions are reactions where a compound breaks into two or more substances as a result of an external pressure. For example, the electrolysis of water results in the following:
2H2O --> 2H2 + O2
In the above reaction two water molecules decompose into two molecules of hydrogen and one molecule of oxygen. Essentially, 2 molecules of the reactant are decomposing to form 3 molecules of the product – so a decomposition reaction must have occurred.
c) Single displacement reactions are reactions where one atom or ion of a single compound is replaced by another atom/ion. Consider the following reaction:
CuO + Zn --> ZnO + Cu
In the above reaction, copper in CuO is being replaced by zinc to form ZnO and Cu.
Thus, understanding these basic reactions will help understand the more complex inorganic behaviors which are built upon these simple principles.
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