What are the spectator ions in the reaction between KCl (aq) and AgNO3 (aq)? A) K+ and Ag+ B) Ag+ and Cl- C) K+ and NO3 – D) Ag+ and NO3 What are the spectator ions in the reaction between KCl (aq) and AgNO3 (aq)? A) K+ and Ag+ B) Ag+ and Cl- C) K+ and NO3 – D) Ag+ and NO3
The Correct Answer and Explanation is :
The correct answer is C) K⁺ and NO₃⁻.
Explanation:
When potassium chloride (KCl) and silver nitrate (AgNO₃) are mixed in aqueous solution, a double displacement (precipitation) reaction occurs. The chemical equation is: KCl (aq)+AgNO₃ (aq)→AgCl (s)+KNO₃ (aq)\text{KCl (aq)} + \text{AgNO₃ (aq)} \rightarrow \text{AgCl (s)} + \text{KNO₃ (aq)}
Here’s a breakdown of the reaction:
- Dissociation of Ionic Compounds in Water:
- KCl dissociates into K⁺ and Cl⁻ ions.
- AgNO₃ dissociates into Ag⁺ and NO₃⁻ ions.
- Formation of a Precipitate: Silver chloride (AgCl) is insoluble in water and forms a precipitate: Ag⁺ (aq)+Cl⁻ (aq)→AgCl (s)\text{Ag⁺ (aq)} + \text{Cl⁻ (aq)} \rightarrow \text{AgCl (s)}
- Spectator Ions: The ions that do not participate in forming the precipitate remain in solution as spectator ions. These are K⁺ and NO₃⁻, as they do not combine to form a solid or undergo any chemical change.
- Net Ionic Equation: The net ionic equation, showing only the species involved in the chemical change, is: Ag⁺ (aq)+Cl⁻ (aq)→AgCl (s)\text{Ag⁺ (aq)} + \text{Cl⁻ (aq)} \rightarrow \text{AgCl (s)} The K⁺ and NO₃⁻ ions are not included here because they do not take part in the reaction; they remain unchanged in the solution.
Why C is the Correct Answer:
K⁺ and NO₃⁻ are the spectator ions since they do not react or change during the chemical process. They are present in the solution both before and after the reaction, making them the correct choice.