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Question
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Solution
Decomposition reactions occur when a compound breaks up into two or more simpler substances. On the other hand, combination reactions occur when two or more substances combine to form a single substance.
Thus, decomposition reactions are the opposite of combination reactions.
Decomposition Reactions:
\[\ce{CaCO3(s) -> CaO(s) + CO2(g)}\]
\[\ce{2H2O(l) ->[Electricity] 2H2(g) + O2(g)}\]
Combination Reactions:
\[\ce{2H2(g) + O2(g) -> 2H2O(l)}\]
\[\ce{NH3(g) + HCl(g) -> NH4Cl(s)}\]
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