### Chapter 1: Chemical reactions and equations

Q
##### Chemical reactions and equations

Question:

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

In a decomposition reaction, the single reactant breaks down to form simpler products is called decomposition reaction. For example, when an electric current is passed through water, the water decomposed to form hydrogen gas along with oxygen gas.

2 H2O (l) ${\color{Blue} \xrightarrow [ ]{ electricity } \$  2 H2 (g) + O2 (g)

But in a combination reaction, a single product is formed from two or more reactants. For example, water is formed by the combination of hydrogen and oxygen gas.

2 H2 (g) + O2 (g) → 2 H­2O (l)

Hence, the decomposition reaction is the opposite of a combination reaction.

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