Question

Observe the following chemical equation. And answer the questions.
$Pb{\left( {N{O_3}} \right)_2} + 2KI \to Pb{I_2} + 2KN{O_3}$
A.What are the reactants?
B.What are the products?
C.Which type of chemical reaction is it?
D.What is the colour of $Pb{I_2}$?

Answer 1

We know that a substance(s) that is present to the left side of the arrow in the chemical equations are reactants and the substances that are present to the right ride of the arrow in chemical equations are products. In the given reaction, we can see the cations and the anions are exchanged, so it must be displacement reactions.

Complete step by step answer:
The given chemical equation is,
$Pb{\left( {N{O_3}} \right)_2} + 2KI \to Pb{I_2} + 2KN{O_3}$
We can see that lead nitrate is reacted with potassium iodide to give lead (II) iodide and potassium nitrate.

(i) Reactants
We can define reactant as a substance(s) that is taking part in the start of a chemical reaction. In a chemical equation, the reactant is present to the left side of the arrow.
So, the reactants in the given reaction are lead nitrate $\left( {Pb{{\left( {N{O_3}} \right)}_2}} \right)$ and potassium iodide $\left( {KI} \right)$.

(ii) Products
We can define a product as a substance(s) that is formed at the end of the chemical reactant. In a chemical equation, the products formed are present to the right side of the arrow.
So, the products formed in the given reaction are lead (II) iodide $\left( {Pb{I_2}} \right)$ and potassium nitrate $\left( {KN{O_3}} \right)$.

(iii) Type of chemical reaction
We can say that the reaction of lead nitrate with potassium iodide to give lead (II) iodide and potassium nitrate are double displacement reactions.
Double displacement reactions take place when the cation and the anions are interchanged between two reactants to form new products. In order for the reaction to occur, one of the products is usually a solid precipitate, a gas or a molecular compound.
The given chemical equation is,
$Pb{\left( {N{O_3}} \right)_2} + 2KI \to Pb{I_2} + 2KN{O_3}$
In the reaction of lead nitrate and potassium iodide, the displacement of the anions of the two reactants takes place, and two new products are formed.

(iv) Colour of $Pb{I_2}$
The colour of lead (II) iodide is bright yellow. It is found as crystalline solid, which turns orange and red on heating. Plumbous iodide is the other name of lead (II) iodide.

Note:
We can use lead (II) iodide in the fabrication of solar cells. We can also use it as a high energy detector for x-rays and gamma rays. It was used as paint pigment. Lead (II) iodide is highly toxic to the health of humans.