Combination reactions are those reactions in which two or more reactants (elements and / or compounds) combine to produce a single product.
It means, no side product is formed during such reactions. Heat changes may take place during the reaction.
Examples of combination reactions
Calcium oxide or quick lime reacts with water to give calcium hydroxide or slaked lime [Ca(OH)2 ]. It is used for white washing walls. It reacts slowly with CO2 in air and form a thin layer of calcium carbonate on the walls after 2 – 3 days of white washing and gives a shiny finish.
Ca(OH)2 (aq) + CO2 (g) →CaCO3 (s) + H2O(l)
Which of the reaction is not a combination reaction ?
(a) CaO + H2O → Ca(OH)2
(b) CaO + CO2 → CaCO3
(c) NH3 + HCl → NH4Cl
(d) CaCO3 → CaO + CO2
Define and give one example of combination reaction.