Question

kai creates his potassium permanganate solution and combines it with ethene (c₂h₄), resulting in the following reaction. identify the spectator ion in the reaction.
3c₂h₄(l) + 2kmno₄(aq) + 4h₂o(l) → 3c₂h₆o₂(l) + 2mno₂(s) + 2koh(aq)
enter the answer choice number.

1. h⁺ 2. mno₄⁻
2. k⁺ 4. o²⁻

Explanation:

A spectator ion is an ion that does not participate in the chemical reaction and remains in the same form on both sides of the reaction. Let's analyze the reaction:

• For \( \ce{KMnO4(aq)} \), it dissociates into \( \ce{K+} \) and \( \ce{MnO4-} \) in aqueous solution.
• For \( \ce{KOH(aq)} \), it dissociates into \( \ce{K+} \) and \( \ce{OH-} \) in aqueous solution.

Looking at the ions:

• \( \ce{MnO4-} \) is involved in the reaction (it is reduced to \( \ce{MnO2} \)), so it is not a spectator ion.
• \( \ce{H+} \) is not present as a free ion in the given reactants or products in the way to be a spectator (the reaction involves water and formation of \( \ce{KOH} \), not free \( \ce{H+} \) in the relevant sense here).
• \( \ce{O^{2-}} \) is not a free ion in this aqueous reaction context (oxides like \( \ce{O^{2-}} \) are not present as free ions in these aqueous solutions).
• \( \ce{K+} \) is present in \( \ce{KMnO4} \) (as \( \ce{K+} \)) and in \( \ce{KOH} \) (as \( \ce{K+} \)), and it does not undergo any chemical change (it is just a cation that stays as \( \ce{K+} \) throughout the reaction, not participating in the redox or other chemical changes). So \( \ce{K+} \) is the spectator ion.

Answer:

1. \( \ce{K+} \)