Consider the two-step process carried out in aqueous solution at 25 °C
CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
Consider the two-step process carried out in aqueous solution at 25 °C.
Step 1: Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq)
Step 2: FeSCN²⁺(aq) + 6 F⁻(aq) → [FeF₆]³⁻(aq) + SCN⁻(aq)
Which of the following best explains why SCN⁻ does not appear in the overall net ionic equation for the process?
(a) SCN⁻ is a spectator ion that never participates in either reaction step.
(b) SCN⁻ is produced and consumed in equal amounts, so it cancels as an intermediate when the two steps are summed.
(c) SCN⁻ acts as a catalyst for the reaction, and catalysts do not appear in the overall net ionic equation.
(d) SCN⁻ is converted completely into FeSCN²⁺ during the first step, so no SCN⁻ remains to appear in the net ionic equation.