Question

Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation for the reactions:
A.Zinc reacts with silver nitrate to produce zinc nitrate and silver.
B. Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

Answer 1

Hint: To answer this question, you should recall the concept of displacement reactions. A displacement reaction is where there is a displacement of atoms to form a new molecule. In general, elements that form anions can replace the anion in a compound, and elements that form cations can replace the cation in a compound.

Complete step by step answer:
We know that in a displacement reaction there is an exchange of ions of reactant particles. Now let’s analyse the reactions given in our question
A.The given reaction is a displacement reaction in which more reactive zinc will displace less reactive silver from silver nitrate solution.
\[Zn\left( s \right) + 2AgN{O_3}\left( {aq.} \right) \to Zn{(N{O_3})_2}\left( {aq.} \right) + 2Ag\left( s \right)\] ​
A displacement reaction is the one in which an entity is displaced by a more reactive atom in the molecule. \[{\text{A }} + {\text{ B}} - {\text{C }} \to {\text{ A}} - {\text{C }} + {\text{ B}}\]
B. The given reaction is a double displacement reaction.
\[2{\text{KI}}\left( {{\text{aq}}{\text{.}}} \right) + {\text{Pb(N}}{{\text{O}}_{\text{3}}}_{{\text{)}}_{\text{2}}}\left( {{\text{aq}}{\text{.}}} \right) \to 2{\text{KN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}{\text{.}}} \right) + {\text{Pb}}{{\text{I}}_{\text{2}}}\left( {\text{s}} \right)\]
Double displacement reaction is the reaction in which there is an exchange of ions to form new compounds. In this reaction, the positive ions exchange with the negative ion. A general equation can be written as:
\[{\text{AB }} + {\text{ CD }} \to {\text{ AD }} + {\text{ CB}}\]
The reactants are two compounds and the products are two different compounds.

Note:
You should remember that metals will usually form cations in the displacement reaction. This includes groups 1 and 2, some of group 13 and 14 elements, and the transition metals. Most common non-metals in single displacement reactions are the group 17 elements, in which generally form anions with a -1 charge.