Chapter 9, Problem 9.1KSP

What is the balanced net ionic equation for the precipitation of FeSO₄(s) when aqueous solutions of K₂SO₄ and FeCl₂ are combined?

(a) $2{\text{K}}^{+}(aq)+{\text{ SO}}_4^{2-}(aq)+{\text{ Fe}}^{2+}(aq){\text{ + 2Cl}}^{-}(aq)\to {\text{ FeSO}}_4(s){\text{ + 2K}}^{+}(aq)+2{\text{Cl}}^{-}(aq)$

(b) ${\text{Fe}}^{2+}(aq)+{\text{ SO}}_4^{2-}(aq)\to {\text{ FeSO}}_{\text{4}}(s)$

(c) ${\text{K}}_2{\text{SO}}_{\text{4}}(aq)\text{ +}\text{}{\text{ FeCl}}_{\text{2}}(aq)\to {\text{ FeSO}}_{\text{4}}(s)\text{ +}\text{}\text{2KCl(}aq\text{)}$

(d) ${\text{Fe}}^{2+}(aq)+{\text{ 2SO}}_4^{2-}(aq)\to {\text{ FeSO}}_{\text{4}}(s)$

(e) $2{\text{K}}^{+}(aq)+{\text{ SO}}_4^{2-}(aq){\text{ + Fe}}^{2+}(aq){\text{ + 2Cl}}^{-}(aq)\to {\text{ FeSO}}_{\text{4}}(s)$

Interpretation Introduction

Interpretation:

The net ionic equation for the precipitation of ${\text{FeSO}}_{\text{4(s)}}$ from ${\text{FeCl}}_{\text{2(aq)}}$ reacted with $K_{\text{2}}S{O}_{\text{4(aq)}}$ should be found from the given set of options.

Concept introduction:

Balanced equation:

• The balanced equation is nothing but the all ionic compounds are represented as neutral compounds using their molecular formulas.
• In the balanced equation, the number of atoms for each element and total charge are equal in the reaction for in both reactants and the products sides.

Ionic equation:

• In the ionic reactions, all the species present in reaction are written with respective charges is called ionic equation.

Net ionic equation:

• The removal of spectator ions from ionic equation to give net ionic equation.

Answer to Problem 9.1KSP

The net ionic equation for the precipitation of ${\text{FeSO}}_{\text{4(s)}}$ from ${\text{FeCl}}_{\text{2(aq)}}$ react with $K_{\text{2}}S{O}_{\text{4(aq)}}$ is,

${\text{(b) Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+SO}}_4{{}^{\text{2-}}}_{\text{(aq)}}\to FeS{O}_{4(s)}$

Explanation of Solution

To give a net ionic equation for the reaction of ${\text{FeCl}}_{\text{2(aq)}}$ react with $K_{\text{2}}S{O}_{\text{4(aq)}}$

Reason for the correct option:

• The ionic compounds are dissolved in water to produced ions; these ions are combined to give new product.
• The ${\text{FeCl}}_{\text{2(aq)}}$ and $K_{\text{2}}S{O}_{\text{4(aq)}}$ are react to give the ${\text{FeSO}}_{\text{4(s)}}$ so the balanced equation for this reaction is,

${\text{FeCl}}_{\text{2(aq)}}+K_{\text{2}}S{O}_{\text{4(aq)}}\to {\text{FeSO}}_{\text{4(s)}}+2KC{l}_{(aq)}$

• The all the species present in above equation is writing with respective charges to give ionic reaction.

${\text{Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+2Cl}}^{\text{-}}{}_{\text{(aq)}}+2K^{+}{}_{\text{(aq)}}+S{O}_4{{}^{2-}}_{\text{(aq)}}\to {\text{FeSO}}_{\text{4(s)}}+2K^{+}{}_{\text{(aq)}}+{\text{2Cl}}^{\text{-}}{}_{\text{(aq)}}$

• The removal of spectator ions forms the above equations to give net ionic equations.

${\text{Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+SO}}_4{{}^{\text{2-}}}_{\text{(aq)}}\to FeS{O}_{4(s)}$

• Hence correct option is ${\text{(b) Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+SO}}_4{{}^{\text{2-}}}_{\text{(aq)}}\to FeS{O}_{4(s)}$

Reason for the incorrect option:

• According to the above ionic and net ionic equations the correct net ionic equation is,

  ${\text{Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+SO}}_4{{}^{\text{2-}}}_{\text{(aq)}}\to FeS{O}_{4(s)}$

• Hence the incorrect options are (a), (c), (d) and (e).

Conclusion

The net ionic equation for the precipitation of ${\text{FeSO}}_{\text{4(s)}}$ from ${\text{FeCl}}_{\text{2(aq)}}$ react with $K_{\text{2}}S{O}_{\text{4(aq)}}$ was found as option ${\text{(b) Fe}}^{\text{2+}}{}_{\text{(aq)}}{\text{+SO}}_4{{}^{\text{2-}}}_{\text{(aq)}}\to FeS{O}_{4(s)}$.