Question

Why are decomposition reactions called the opposite of Combination reactions? Write equations for decomposition reactions.
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Answer 1

Answer:

Explanation:

In a combination reaction two or more substances are combined to form new substance while in the decomposition reaction one substance decomposes into two or more substances. Hence, the decomposition reactions are called opposite of combination reactions.

Decomposition reaction CaCO₃ (s) ⇨ CaO (s) + CO₂ (g)

Combination reaction H₂ (g) + Cl₂ ⇨ 2HCl (g)

Answer 2

Answer:

• In decomposition reaction, a compound is broken into simpler compounds or elements for e.g.:-  
• CuCO3 → CuO + CO2

• Whereas in combination reaction, two or more compounds or elements combine to form a new compound for e.g.:-

• N2(g) + 3H2(g) → 2NH3(g)

Thus, decomposition and combination reactions are opposite to each other.