# Question Video: Writing the Equation for 𝐾_𝑐 in the Reduction of Iron(II) Ions by Silver Ions Chemistry

Silver ions can be reduced by iron(II) ions in the following net ionic equation: Fe²⁺ (aq) + Ag⁺ (aq) ⇌ Fe³⁺ (aq) + Ag (s). What is the correct equation for 𝐾_c for this reaction?

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### Video Transcript

Silver ions can be reduced by iron(II) ions in the following net ionic equation. Fe2+ aqueous plus Ag+ aqueous are in equilibrium with Fe3+ aqueous plus Ag solid. What is the correct equation for 𝐾 𝑐 for this reaction?

𝐾 𝑐 is the equilibrium constant. An equilibrium constant is a value that expresses the relationship between reactant and product concentrations at equilibrium. Let’s consider this generic equilibrium reaction equation.

In this equation, the lowercase letters represent molar coefficients and the uppercase letters represent chemical formulas. The equation for the equilibrium constant for this reaction would be 𝐾 𝑐 equals the concentration of the products raised to their molar coefficients divided by the concentration of the reactants raised to their molar coefficients.

It’s important to note that species in the solid phase and pure water when used as a solvent are not included in the equilibrium constant equation. We can apply all of this information to the reaction given in the question. We can see that silver is a solid in this chemical reaction. So it won’t be included in the equilibrium constant equation. Following the generic equation for an equilibrium constant, we can write the equilibrium constant equation for this reaction, omitting silver because it is a solid.

In conclusion, the correct equilibrium constant equation for the given reaction is 𝐾 𝑐 equals the concentration of Fe3+ divided by the concentration of Fe2+ times the concentration of Ag+.