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Decomposition Reactions

A decomposition reaction is the opposite of a synthesis reaction. In a decomposition reaction a reactant compound is broken into two or more less complex substances. you are given a compound as the reactant. In most cases, to find the product you split the compound into the individual elements. The other types of decomposition reactions (decomposition of a hydrate, chlorate, carbonate, etc.) are covered in other tutorials. This tutorial focuses on the decomposition of a binary compound. The general pattern of a decomposition reaction is:
AB --> A + B
Look at the example below.
Example #1:
2H
2O(l) --> 2H2(g) + O2(g)
Water decomposes (usually with the help of electricity) to form hydrogen gas and oxygen gas. Hydrogen and oxygen are written with subscripts of 2 because they are both diatomic molecules.
Now letâ€™s go step by step.
Predict the products when solid iron(II) oxide decomposes.
 Description of Action Action 1. Write the formula for the given reactant. FeO(s) --> 2. On the products side of the equation, write the symbols for the two elements in the compound. Be sure to separate the elements by a + sign. If either of the elements is diatomic, be sure to write a 2 as its subscript. FeO(s) --> Fe(s) + O2(g) Oxygen is diatomic, so it is written with a subscript of 2. 3. Balance the equation. 2FeO(s) --> 2Fe(s) + O2(g)

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