Question

When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, white precipitate is formed. Give the chemical equation of this reaction.

Answer 1

To answer this question, we only need to understand what a double displacement reaction is. When two compounds react by an exchange of ions to form new compounds are called double displacement reactions.

Complete answer:
As we said in double displacement the reactants will be two compounds and the product will be another two compounds.
For example, $AB + CD \to AD + CB$
Here we have to keep in mind that we should not swap both the cation and anions since it will produce the same product as the reactant is. Therefore, the ionic swapping is such that the formed product is not the same as reactant. Also, many of the double displacement reactions occur between ionic compounds that are dissolved in water.
Now, coming to our question we have an aqueous solution containing potassium chloride. The molecular formula for potassium chloride is $KCl$ and an aqueous solution of silver nitrate, the molecular formula for silver nitrate is $AgN{O_3}$. So to identify whether the reaction is double displacement we have to understand that all the precipitation and neutralisation reactions are mostly double displacement reactions. Here we have given that a white precipitate is formed which indicates the precipitate reaction, hence, we can confirm that the reaction is a double displacement reaction.
This $KCl$ solution is added to $AgN{O_3}$ solution resulting in a double displacement reaction. ${K^ + }$ will try to combine with $N{O_3}^ -$ whereas $A{g^ + }$ tries to combine with $C{l^ - }$. The resulting reaction will be
$KC{l_{\left( {aq} \right)}} + AgN{O_{3\left( {aq} \right)}} \to KN{O_{3\left( {aq} \right)}} + AgC{l_{\left( s \right)}}$

Note:
Here, the white precipitate formed is due to the formation of silver chloride. This is an indication of double displacement reaction. Also, keep in mind to balance the reaction always as the cations and anions are interchanged the reaction may not be balanced