Question

“Reaction of Potassium iodide with lead nitrate solution” is the example of:
A.Chemical Replacement reaction
B.Neutralisation reaction
C.Precipitation reaction
D.Chemical double decomposition reaction

Answer 1

Hint: A reaction in which an insoluble solid substance is formed is known as a precipitation reaction. In short, the formation of a precipitate is known as a precipitation reaction. The reaction between Potassium iodide and lead nitrate leads to the formation of lead iodide and potassium nitrate.

Complete answer:
First let us see the balanced chemical reaction between Potassium iodide and lead nitrate.
\[Pb{{\left( N{{O}_{3}} \right)}_{2\left( aq \right)\text{ }}}+\text{ }2K{{I}_{\left( aq \right)}}\to \text{ }Pb{{I}_{2\left( s \right)}}+\text{ }2KN{{O}_{3\left( aq \right)}}\]
When aqueous lead nitrate is added to potassium iodide, Iodide ion displaces nitrate from lead nitrate and Nitrate displaces iodine from potassium iodide. Thus, two new products, Potassium nitrate and lead iodide are formed. This is an example of a double displacement reaction.
Also, the products formed have a peculiar colour. The colour of Potassium nitrate formed is white and that of lead nitrate is Yellow.
The compound lead iodide (\[Pb{{I}_{2}}\]) is the precipitate formed. Yellow particles of lead iodide can be observed in the reaction mixture which indicates that a chemical change has taken place.
We’ll now see how the precipitate lead iodide is formed by gaining two iodide ions.
The net equation is represented as-
\[P{{b}^{2+}}_{(aq)}+2{{I}^{-}}_{(aq)}\to Pb{{I}_{2(s)}}\]
Due to the formation of precipitate \[Pb{{I}_{2}}\](lead iodide) the reaction between Potassium iodide and lead nitrate is a an example of a “PRECIPITATION REACTION”.
The correct answer is OPTION C- PRECIPITATION REACTION.

Additional information:
Lead Iodide is used as ‘Artist’s pigment’ and is thus called Iodine yellow because of its bright yellow appearance. Pure \[Pb{{I}_{2}}\]is useful to fabricate X-ray and gamma ray detectors.

Note:
All iodide salts are soluble compounds except lead iodide which appears as an insoluble yellow precipitate.