Question

Name the type of the following chemical reaction.
$2KCl{{O}_{3}}\to 2KCl+3{{O}_{2}}$
A) Combination
B) Decomposition
C) Displacement
D) precipitation

Answer 1

There are several types of chemical reactions which are known to us, but in order to determine the type of a specific chemical reaction we must look for the number of reactants it contains. If it is a combination reaction, it should have two or more reactants, in decomposition it only has one reactant, while in case of displacement, at least two different reactants are needed and as per the precipitation reaction, two solutions containing soluble salts are needed.

Complete answer:
In order to answer this question, we must first understand all these types of reactions which are mentioned in the options.
The first combination reaction, which is also termed as the synthesis reaction is a type of reaction which involves a combination of two or more substances in order to form a single new substance with different chemical and physical properties. So this reaction can be generally represented as
$A+B\to AB$
Where $A$ and $B$ are the reactant and $AB$ is the product. Now as a specific example we can use the formation of sodium chloride. This reaction involves a combination of sodium and chloride in order to form sodium chloride. This can be chemically represented as,
$Na(s)+C{{l}_{2}}(g)\to 2NaCl(s)$
Now, if we consider the next option which is decomposition reaction, it is where one reactant breaks down in order to form two or more products. It is the opposite of the combination reaction. The general formula could be
$AB\to A+B$
An example of decomposition reaction could be the decomposition of sodium hydroxide in order to form sodium oxide and water as a side product. This equation can be chemically represented as,
$2NaOH(s)\to N{{a}_{2}}O(s)+{{H}_{2}}O(g)$
Now, the next option says displacement reaction, as the name suggests some element gets displaced by the other element in a compound, depending upon certain criteria. It can be generally represented as
$A+BC\to AC+B$
Here, as we can see the element $A$ replaces element $B$ from the reactant $BC$, and forms $AC$ as the product and the $B$ remains isolated in the product. An example of this reaction would be $Zn(s)+2HCl(aq)\to ZnC{{l}_{2}}(aq)+{{H}_{2}}(g)$
Here we can see the zinc replaces hydrogen from hydrogen chloride in order to form zinc chloride.
Now the last option says precipitation reaction, which refers to the reaction in which formation of insoluble precipitates takes place when two or more solutions which contain soluble salts, are combined with each other. General formula for precipitation reaction would be $AB(aq)+CD(aq)\to AC(s)+BD(aq)$
Here the precipitate is $AC$ which is formed by the combination of two solutions $AB$ and $CD$. A specific example would be
$AgN{{O}_{3~}}(aq){ }+{ }KCl{ }(aq){ }\to { }AgCl{ }(s){ }+{ }KN{{O}_{3}}(aq)$
Here, silver nitrate reacts with potassium chloride, both in aqueous medium, in order to form silver chloride which is insoluble precipitate and potassium nitrate.
Now if we consider the equation given in the question, $2KCl{{O}_{3}}\to 2KCl+3{{O}_{2}}$, we can see that only one reactant breaks down in order to form two products, which is clearly an example of decomposition reaction.

Hence the correct option is option B.

Note: Combination reaction involves combination of two or more reactants in order to form a product. While in case of decomposition reaction it is exactly the opposite, which is, decomposition or breaking down of a reactant in order to form two or more products.
Displacement reaction is the one, where an element of a compound gets replaced by another element, while in case of precipitation reaction, two solutions having soluble salts combine with each other in order to form an insoluble salt which comes out as the precipitate.