Questions: Refer to the following incomplete precipitation reaction: Ni2(SO3)3(aq) + (NH4)3PO4(aq) → a. For the reaction above, provide the balanced molecular equation. Be sure to include states of matter and show all work.

Solution Steps

The given reaction involves nickel(III) sulfite, $\mathrm{Ni}_{2}\left(\mathrm{SO}_{3}\right)_{3}$, and ammonium phosphate, $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$. These reactants are in aqueous form, as indicated by the (aq) state. The reaction is a precipitation reaction, which typically results in the formation of an insoluble solid (precipitate) and possibly other soluble products.

In a precipitation reaction, the cations and anions from the reactants exchange partners. The possible products are nickel(III) phosphate, $\mathrm{NiPO}_{4}$, and ammonium sulfite, $\mathrm{(NH}_{4})_{2}\mathrm{SO}_{3}$.

The unbalanced molecular equation for the reaction is: $$\mathrm{Ni}_{2}\left(\mathrm{SO}_{3}\right)_{3}(aq) + \left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}(aq) \rightarrow \mathrm{NiPO}_{4}(s) + \mathrm{(NH}_{4})_{2}\mathrm{SO}_{3}(aq)$$

To balance the equation, ensure that the number of each type of atom is the same on both sides of the equation.

1. Nickel (Ni): There are 2 Ni atoms in $\mathrm{Ni}_{2}\left(\mathrm{SO}_{3}\right)_{3}$, so we need 2 $\mathrm{NiPO}_{4}$ on the product side.
2. Sulfite (SO$_3$): There are 3 SO$_3$ groups in $\mathrm{Ni}_{2}\left(\mathrm{SO}_{3}\right)_{3}$, so we need 3 $\mathrm{(NH}_{4})_{2}\mathrm{SO}_{3}$ on the product side.
3. Ammonium (NH$_4$): There are 3 NH$_4$ groups in $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$, so we need 2 $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$ on the reactant side to balance with 3 $\mathrm{(NH}_{4})_{2}\mathrm{SO}_{3}$.

The balanced equation is: $$\mathrm{Ni}_{2}\left(\mathrm{SO}_{3}\right)_{3}(aq) + 2\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}(aq) \rightarrow 2\mathrm{NiPO}_{4}(s) + 3\mathrm{(NH}_{4})_{2}\mathrm{SO}_{3}(aq)$$

Final Answer