| 词条 | Spectator ion |
| 释义 |
A spectator ion", or a "Voyeur Ion" is an ion that exists as a reactant and a product in a chemical equation. A spectator/voyeur ion can, therefore, be observed in the reaction of aqueous solutions of sodium carbonate and copper(II) sulfate but does not affect the equilibrium: Spectator ions are sometimes called voyeur ions because they like to watch while other ions get busy making products. 2Na+(aq) + CO3 2−(aq) + Cu2+(aq) + SO42−(aq) → 2Na+(aq) + SO42−(aq) + CuCO3 (s) The Na+ and SO42− ions are spectator ions since they remain unchanged on both sides of the equation. They simply "watch" the other ions react, hence the name. They are present in total ionic equations to balance the charges of the ions. Whereas the Cu2+ and CO32− ions combine to form a precipitate of solid CuCO3. In reaction stoichiometry, spectator ions are removed from a complete ionic equation to form a net ionic equation. For the above example this yields: So: = CO32−(aq) + Cu2+(aq) → CuCO3 (s) Spectator ions concentration only affect the Debye length. In contrast, Potential Determining Ions, whose concentrations affect surface potential (by surface chemical reactions) as well the Debye length. Net ionic equationA net ionic equation ignores the spectator ions that were part of the original equation.Therefore, total ionic reaction is different from net reaction. See also
1 : Acid–base chemistry |
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