Question

In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate solution, a yellow precipitate of lead iodide is obtained. While performing the activity if lead nitrate is not available, which of the following can be used in the place of lead nitrate?
(A). Lead sulphate
(B). Lead acetate
(C). Ammonium nitrate
(D). Potassium sulphate

Answer 1

- Hint: The compound which can be used in place of lead nitrate is the compound whose molecular weight is 325.29g/mol. It is a white efflorescent monoclinic compound and used as a mordant in textile printing and dyeing.

Complete step-by-step solution -
Let us first know about the double displacement reaction-
Double displacement reactions are also called exchange reaction or metathesis reaction. It takes place when parts of two ionic compounds are exchanged, making two new compounds. The overall pattern of the double displacement reaction is like-
${{\text{A}}^{+}}{{\text{B}}^{-}}\text{+}{{\text{C}}^{+}}{{\text{D}}^{-}}\to {{\text{A}}^{+}}{{\text{D}}^{-}}\text{+}{{\text{C}}^{+}}{{\text{B}}^{-}}$
This reaction generally takes place in aqueous medium and the react and products produced are usually the ionic compounds.
Here, in this question, the reaction undergoes in following manner-
$\text{KI+Pb(N}{{\text{O}}_{3}}{{)}_{2}}\to \text{KN}{{\text{O}}_{3}}+\text{Pb}{{\text{I}}_{2}}$
If lead nitrate is not present, then from options we can’t take lead sulphate because it is not soluble in water. So, the reaction will not proceed accordingly.
We also can’t take ammonium nitrate and potassium sulphate because lead is not present in that ionic salt. So, the compound that is left is the right choice and reaction proceeds accordingly.
$\text{Pb(C}{{\text{H}}_{3}}\text{COO}{{\text{)}}_{2}}+2\text{KI}\to \text{Pb}{{\text{I}}_{2}}+2\text{C}{{\text{H}}_{3}}\text{COOK}$

Note: It should be noted that neutralization reactions are a type of double replacement reaction that occurs between an acid and a base. An aqueous neutralization reaction generally produces water and a new ionic compound which is also called salt.