Question

A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention that type of the chemical reaction?

Answer 1

Firstly, let's write the chemical equation of the above-mentioned reaction which may give us the lead to answer this question. KCl and $AgN{O_3}$ are ionic salts when dissolved in water it dissociates as constituent ions ${K^ + }$ , $C{l^ - }$ , $A{g^ + }$and $NO_3^ -$.

Complete answer:
Silver chloride (AgCl) is formed as an insoluble white precipitate when aqueous solution of potassium chloride (KCl) and silver nitrate ($AgN{O_3}$) are mixed.
The chemical reaction is:
$KCl + AgN{O_3} \to AgCl + KN{O_3}$
When $A{g^ + }$and $C{l^ - }$ comes in contact it forms a precipitate of AgCl which appears as a milky, cloudiness in the solution and finally yield as a white powder at the bottom of the test-tube.
Let’s see into it in depth with the help of basic definitions that are required to understand the essence of this question and apply the logic to this question.
Definition of precipitation reaction: when two solutions containing soluble salts are mixed together forming insoluble salts. This insoluble salt is known as precipitate and this kind of reaction is known as precipitation reaction.
$KCl + AgN{O_3} \to AgCl + KN{O_3}$
Here potassium chloride and silver nitrate both are soluble salts. Its solution is mixed together and a white insoluble salt of silver chloride is given out as a precipitate. This exactly satisfies the definition of precipitation reaction. This reaction is also an example of another type of reaction; let's see what that is. To know this we should know the definition of double displacement reaction at the first space.
Definition of double displacement reaction: The chemical reaction where cations and anions of two different compounds exchange their ions are known as double displacement reaction.
${K^ + }C{l^ - } + A{g^ + }NO_3^ - \to A{g^ + }C{l^ - } + {K^ + }NO_3^ -$
In potassium chloride, ${K^ + }$ is a cation and $C{l^ - }$ is an anion and in silver nitrate $A{g^ + }$ is cation and $NO_3^ -$ is an anion. If we observe the reaction mentioned above, we can make out there is exchange of anions $C{l^ - }$and $NO_3^ -$ with cations ${K^ + }$and $A{g^ + }$ respectively. Therefore, this explanation too meets the definition of double displacement reaction. Hence this reaction is a precipitation as well as double displacement reaction.

Note:
This reaction is an example of both the precipitation as well double displacement reaction. Since, $AgN{O_3}$ and KCl easily dissociates into constituent ions which displace and form new compounds. In this reaction AgCl precipitates. This reaction exactly tallies with the definition of precipitate and double displacement reaction as mentioned above.