Spectator Ions

[Anna Hilger 3H]

How can you identify spectator ions? I heard Dr. Lavelle say in lecture that strong acids don't affect pH, how does that work?

[Lauren Woodward 1I]

Strong acids do affect pH, because placing a strong acid into water will cause it to ionize and lower the pH of the solution. Spectator ions are the cations of strong bases (group 1 & 2 metals) and the anions of strong acids (ie Cl, Br, I, NO3, ClO4, and H2SO4). When strong acids dissociate, they dissociate completely, so an anion of a strong acid would not react with any of the ions in the solution, because it would not want to reform the strong acid. So for example a Cl- ion wouldn't react with an H+ from H20 to reform HCl, because HCl would dissociate completely in water. My understanding of this is a little shaky but I hope this helps a little bit.

[Anna Hilger 3H]

That makes sense. Thank you so much!!