Question

Define combination reaction. Give one example of combination reaction which is exothermic in nature.

Answer 1

In combination reactions, two or more substances combine to form a new compound. Only one product is obtained in such reactions. The reactants in such reactions can be elements as well as compounds.
For Example, Calcium oxide reacts with water to produce calcium hydroxide. 

Answer 2

Combination reactions and one example of a combination reaction that is exothermic are:

• There are many types of reactions such as combination, displacement, double displacement and neutralisation reactions.
• In combination reaction product is formed by the combination of two or more reactants.
• An example of an exothermic combination reaction is- CaCO3 → CaO+ CO2
• In displacement reaction displacement of one of the reactant occur and a new product is formed.
• An example of a displacement reaction is Fe2O3+3CO→2Fe+3CO 2. In this reaction, oxygen is displaced from Fe203 but not displacement from CO.
• In a double displacement reaction, displacement of both the reacting molecules occurs. for example- CuSO4+ 2NaOH → Cu(OH)2 + Na2SO4. in this reaction Cu is displaced from CuSO4 and Na from NaOH. as displacement is occurring in both the reactants.
• A neutralisation reaction is a simple acid-base reaction and salt and water are produced.