Question

When each of the following pairs of aqueous solutions is mixed, does a precipitation reaction occur? If so, write balanced molecular, total ionic, and net ionic equations.

(a) Potassium chloride + iron (III) nitrate

(b) Ammonium sulfate + barium chloride

Short answer

(a) Precipitation reaction does not occur.

(b) Precipitation reaction occurs. The precipitate formed is Barium sulfate.

Step-by-step solution

Write the equation of potassium chloride and iron (III) nitrate

We note the ions present in the reactants for each pair of solutions and write the cation-anion combinations if any of them are insoluble or soluble. For the molecular equation, we predict the products:

$\left(\mathrm{a}\right)3\mathrm{KCl}\left(\mathrm{aq}\right)+\mathrm{Fe}{\left({\mathrm{NO}}_3\right)}_3\left(\mathrm{aq}\right)\to {\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+3{\mathrm{KNO}}_3\left(\mathrm{aq}\right)$

Since these compounds are soluble in aqueous solution hence this reaction does not give a precipitate

All ammonium, sodium, and most perchlorate compounds are soluble, and all bromides, nitrates are soluble except those of Ag⁺, Pb²⁺, Cu⁺, and Hg₂²⁺.

Therefore, the compounds remain dissociated in the solution as solvated ions.

Write the equation of ammonium sulfate and barium chloride

For each pair of solutions, we note the ions present in the reactants and write the cation-anion combinations if any of them are insoluble or soluble. For the molecular equation, we predict the products:

The balanced molecular reaction is:

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+{\mathrm{BaCl}}_2\left(\mathrm{aq}\right)\to 2{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+{\mathrm{BaSO}}_4\left(\mathrm{s}\right)$

The total ionic equation is:

$2{\mathrm{NH}}_4^{+}\left(\mathrm{aq}\right)+{\mathrm{SO}}_4^{2-}\left(\mathrm{aq}\right)+{\mathrm{Ba}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)\to 2{\mathrm{NH}}_4^{+}\left(\mathrm{aq}\right)+2{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)+{\mathrm{BaSO}}_4\left(\mathrm{s}\right)$

The net ionic equation is:

${\mathrm{Ba}}^{2+}\left(\mathrm{aq}\right)+{\mathrm{SO}}_4^{2-}\left(\mathrm{aq}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{s}\right)$

Barium sulfate formed is insoluble in aqueous solution and hence forms precipitate.