$\begin{array}{c} Al \left( NO _3\right)_3( aq ) \text { and } Na _3 PO _4( aq ) \\ Al \left( NO _3\right)_3( aq )+ Na _3 PO _4( aq ) \rightarrow AlPO _4(s) \\ \text { Molecular Equation } \\ Al ^3+( aq )+3 NO _3( aq )+3 Na ^3+( aq )+ PO _4{ }^{3-}( aq ) \\ \text { Complete Ionic Equation } \\ Al ^{3+}( aq )+ PO _4{ }^3 \\ \text { Net Ionic Equation } \\ \text { Spectator Ions }\end{array}$
Answer (1)
The molecular, complete ionic, and net ionic equations are given.
Spectator ions are ions present in the complete ionic equation but not in the net ionic equation.
Comparing the equations, identify N a + and N O 3 − as spectator ions.
The spectator ions are N a + , N O 3 − .
Explanation
Understanding Spectator Ions We are given the molecular equation, the complete ionic equation, and the net ionic equation for the reaction between A l ( N O 3 ) 3 ( a q ) and N a 3 P O 4 ( a q ) . Our goal is to identify the spectator ions. Spectator ions are ions that are present in the reaction mixture but do not participate in the reaction. They appear on both sides of the complete ionic equation but are not included in the net ionic equation.
Reviewing the Equations The molecular equation is: A l ( N O 3 ) 3 ( a q ) + N a 3 P O 4 ( a q ) → A lP O 4 ( s ) + 3 N a N O 3 ( a q ) The complete ionic equation is: A l 3 + ( a q ) + 3 N O 3 − ( a q ) + 3 N a + ( a q ) + P O 4 3 − ( a q ) → A lP O 4 ( s ) + 3 N a + ( a q ) + 3 N O 3 − ( a q ) The net ionic equation is: A l 3 + ( a q ) + P O 4 3 − ( a q ) → A lP O 4 ( s )
Identifying Spectator Ions Comparing the complete ionic equation and the net ionic equation, we can identify the ions that are present in the complete ionic equation but not in the net ionic equation. These are the spectator ions. In the complete ionic equation, we have A l 3 + ( a q ) , N O 3 − ( a q ) , N a + ( a q ) , and P O 4 3 − ( a q ) on the reactant side, and A lP O 4 ( s ) , N a + ( a q ) , and N O 3 − ( a q ) on the product side. In the net ionic equation, we only have A l 3 + ( a q ) and P O 4 3 − ( a q ) forming A lP O 4 ( s ) . Therefore, the spectator ions are N a + ( a q ) and N O 3 − ( a q ) .
Final Answer The spectator ions are sodium ions ( N a + ) and nitrate ions ( N O 3 − ). These ions are present in the solution before and after the reaction, but they do not directly participate in the formation of the solid aluminum phosphate ( A lP O 4 ).
Examples
Spectator ions are like the audience at a play. They are present but do not actively participate in the main action. In chemistry, identifying spectator ions is crucial in understanding the actual chemical changes occurring in a reaction. For instance, in water treatment, understanding which ions are merely 'spectating' helps in designing efficient methods to remove only the harmful contaminants, without unnecessarily altering the water's composition. This ensures that the treatment process is both effective and economical.
