Question

Balance reaction when dilute HCl is added to lead nitrate solution.
(A) \[Pb{{(N{{O}_{2}})}_{2}}+2HCl\to PbC{{l}_{2}}+2HN{{O}_{3}}\]
(B) \[2Pb{{(N{{O}_{3}})}_{2}}+2HCl\to PbC{{l}_{2}}+HN{{O}_{3}}\]
(C) \[Pb{{(N{{O}_{3}})}_{2}}+2HCl\to PbC{{l}_{2}}+2HN{{O}_{3}}\]
(D) \[Pb{{(N{{O}_{3}})}_{2}}+2HCl\to PbC{{l}_{2}}+HN{{O}_{3}}\]

Answer 1

Hint: For example, milk is left at room temperature or food is cooked, or food gets digested in our body. In this situation, the nature and the identity of the initial substance have somewhat changed. Whenever a chemical change occurs, that chemical reaction takes place.

Complete step by step answer:
In this reaction when dilute HCl is added to lead nitrate solution, lead chloride and nitric acid will form.
Lead nitrate + dilute hydrochloric acid Produces lead chloride + nitric acid -- (1)
The substances that undergo chemical change in the above reaction, lead nitrate, and dilute hydrochloric acid are the reactants. The new substance lead chloride and nitric acid are products.
A word equation shows the change of reactants to products through an arrow placed between them. The reactants are written on the left-hand side and products are written on the right-hand side with plus (+) sign between them.
The arrowhead points towards the products show the direction of the reaction.
Chemical equations can be made more concise and useful if we use chemical formulas instead of words. A chemical equation represents a chemical reaction.
For the chemical reaction given, the equation (1) can be written as
\[Pb{{(N{{O}_{3}})}_{2}}+HCl\to PbC{{l}_{2}}+HN{{O}_{3}}\] -- (2)

Count and compare the number of atoms of each element on LHS and RHS of the arrow. Is the number of atoms of each element the same on both sides for the reaction (2)? No, then the equation is unbalanced because the mass is not the same on both sides of the chemical equation. Equation (2) is skeletal as a chemical equation when dilute HCl is added to lead nitrate solution.
Recall the law of conservation of mass, mass can neither be created nor destroyed in a chemical reaction. That is, the total mass of the elements present in the products of the chemical reaction has to be equal to the total mass of elements present in the reactants.
So, the balanced chemical reaction (2) will be,
\[Pb{{(N{{O}_{3}})}_{2}}+2HCl\to PbC{{l}_{2}}+2HN{{O}_{3}}\]

So, the correct answer is “Option C”.

Note: A white precipitate of lead chloride is formed when dilute hydrochloric acid is added to lead nitrate solution at room temperature. On heating, the precipitate gradually dissolves to give an almost clear solution because lead chloride is fairly soluble in hot water. But cooling the precipitate re-appears as lead chloride is much less soluble in cold water.