Chapter 4, Problem 149AP

Interpretation Introduction

Interpretation:

The molecular and ionic equations of the reaction are to be represented and the molar concentration of ${\text{Pb}}^{2+}$

required to react with $0.0045{\text{ g Na}}_2{\text{SO}}_4$ is to be calculated.

Concept introduction:

When ionic compounds dissolve in a solvent, they dissociate into ions. So, the reactions between ions in a solution are known as ionic reactions.

A chemical reaction always follows the law of conservation of mass, according to which when a chemical reaction occurs, the mass of atoms in products should be equal to the mass of atoms in reactants.

The number of moles of a reactant is calculated by the following formula:

$m=\frac{wt}{MW}$

Here, $m$ is the number of moles of the compound, $wt$ is the weight of the compound and $MW$ is the molecular weight of the compound.

The molar concentration of a solution is determined as follows:

$M=\left(m\right)\left(\frac{1}{V}\right)$

Here, $M$ is the concentration of the compound in molarity, $m$ is the number of moles of the compound and $V$ is the volume of solution in litre containing the compound.

$\text{Pb}{\left({\text{NO}}_3\right)}_2\left(aq\right)+{\text{Na}}_2{\text{SO}}_4\left(aq\right)\to {\text{PbSO}}_4\left(s\right)+2{\text{NaNO}}_3\left(aq\right)$

${\text{Pb}}^{2+}\left(aq\right)+{\text{SO}}_{\text{4}}{}^{2-}\left(aq\right)\to {\text{PbSO}}_4\left(s\right)$

(b)

$6.34\times {10}^{-5}\text{M}$.