Question #08b07

1 Answer
Ernest Z. · Antoine
Mar 11, 2014

A spectator ion is an ion that exists as both a reactant and a product in a chemical equation.

Explanation:

Consider the reaction

NaCl(aq)+AgNO3(aq)→AgCl(s)+NaNO3(aq)

The ionic equation is:

Na+(aq)+Cl−(aq)+Ag+(aq)+NO−3(aq)→AgCl(s)+Na+(aq)+NO−3(aq)

The Na+ and NO−3 ions are spectator ions because they remain unchanged on both sides of the equation. They just "watch" the other ions react, hence the name.

We usually cancel the spectator ions from each side of an ionic equation to form a net ionic equation:

Na⁺(aq)+Cl−(aq)+Ag+(aq)+NO₃⁻(aq)→AgCl(s)+Na⁺(aq)+NO₃⁻(aq)

Cl−(aq)+Ag+(aq)→AgCl(s)

EXAMPLE:

Identify the spectator ions and write the net ionic equation for the reaction:

HCl(aq)+NaHCO3(aq)→NaCl(aq)+H2O(l)+CO2(g)

SOLUTION:

Ionic Equation:

H+(aq)+Cl−(aq)+Na+(aq)+HCO−3(aq)→Na+(aq)+Cl−(aq)+H2O(l)+CO₂(g)

The spectator Ions are Cl− and Na+.

Net Ionic Equation:

H+(aq)+Cl⁻(aq)+Na⁺(aq)+HCO−3(aq)→Na⁺(aq)+Cl⁻(aq)+H2O(l)+CO2(g)

H+(aq)+HCO−3(aq)→H2O(l)+CO2(g)

Here is a video on spectator ions

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