Question

\[BaC{{l}_{2}}\left( aq \right)+N{{a}_{2}}S{{O}_{4}}\left( aq \right)\to BaS{{O}_{4}}(s)+2NaCl(aq)\]
The above reaction involves which type of reaction:
a)Displacement
b)Precipitation
c)Combination
d)Double displacement
(A)- (a) & (b)
(B)- (a), (b) & (c)
(C)- (b) & (c)
(D)- (b) & (d)

Answer 1

Hint: In the given reaction, the cation and anion part of reactant and the product formed, can help in determining the nature of reaction as the ions of the reactant molecule displace from its original place as the reaction progresses.

Complete step by step answer:
In the reaction, the reactant has cations as\[B{{a}^{+2}},N{{a}^{+}}\] and anions as \[C{{l}^{-}},SO_{4}^{-2}\],present in the aqueous solution of barium chloride and sodium sulphate. Thus, existing as soluble ions when dissolved in water.
These ions in the aqueous solution displace one another, such that the cations and anions in both the molecules exchange places forming two entirely different molecules, that is, \[BaS{{O}_{4}}\] and \[NaCl\]. Thus, called a double displacement.
The product formed involves sodium chloride,\[NaCl\] which is soluble in aqueous solution and barium sulphate, \[BaS{{O}_{4}}\] which precipitates out as insoluble solid in the solution.
So, the correct answer is “Option D”.

Note: In a combination reaction, two or more compounds in the reactant combine together to form a new product which involves release of energy as it breaks the old bonds and form new ones. For example: reaction of calcium oxide and water forms calcium hydroxide.
\[CaO+{{H}_{2}}O\to Ca{{\left( OH \right)}_{2}}\]

Also, when in a reaction a single element being more reactive replaces another element in the compound which is less reactive to form a stable product is simply known as displacement or a single displacement reaction or a synthesis reaction. For example: reaction of copper sulphate and magnesium gives calcium sulphate and copper as Mg is more reactive than Cu.
\[CuS{{O}_{4}}+Mg\to MgS{{O}_{4}}+Cu\]