For the reaction, Zn (s) and Cu(NO3)2 (aq), write the molecular, complete ionic and net ionic equations. Note: most likely charge on the zinc cation is +2
The correct answer and explanation is :
Molecular Equation:
The molecular equation represents the full reaction in terms of the reactants and products as they exist in their molecular forms:
$$
\text{Zn (s)} + \text{Cu(NO}_3\text{)}_2 \text{(aq)} \rightarrow \text{Cu (s)} + \text{Zn(NO}_3\text{)}_2 \text{(aq)}
$$
Here, zinc metal reacts with copper(II) nitrate in aqueous solution, producing solid copper and zinc nitrate in aqueous solution.
Complete Ionic Equation:
In the complete ionic equation, we break down all aqueous compounds into their constituent ions:
$$
\text{Zn (s)} + \text{Cu}^{2+} \text{(aq)} + 2\text{NO}_3^- \text{(aq)} \rightarrow \text{Cu (s)} + \text{Zn}^{2+} \text{(aq)} + 2\text{NO}_3^- \text{(aq)}
$$
In this equation:
- Zinc (Zn) is a solid and doesn’t break into ions.
- Copper(II) nitrate dissociates into $\text{Cu}^{2+}$ and $\text{NO}_3^-$ ions in solution.
- Zinc nitrate dissociates into $\text{Zn}^{2+}$ and $\text{NO}_3^-$ ions in solution.
Net Ionic Equation:
The net ionic equation is derived by removing spectator ions (ions that appear unchanged on both sides of the equation). In this case, the $\text{NO}_3^-$ ions are spectator ions because they don’t undergo any change during the reaction.
$$
\text{Zn (s)} + \text{Cu}^{2+} \text{(aq)} \rightarrow \text{Cu (s)} + \text{Zn}^{2+} \text{(aq)}
$$
Explanation:
- Zinc (Zn) is in its elemental form (solid) on the left side. It loses two electrons, which are transferred to the copper ions in solution. This oxidation process forms $\text{Zn}^{2+}$ ions.
- Copper(II) ions ($\text{Cu}^{2+}$) in solution gain the two electrons lost by zinc in a reduction process to form copper metal (Cu), which precipitates as a solid.
- The spectator ions are the nitrate ions $\text{NO}_3^-$, which do not change during the reaction and are present on both sides of the equation.
Thus, the molecular, complete ionic, and net ionic equations clearly represent the oxidation of zinc and reduction of copper(II) ions, showcasing a single displacement redox reaction.