Spectator ion

[Megan McKenna Dis1A]

Hello! I am not sure that I understand what spectator ions are and their role in the equation. Could someone please explain this?

It came up on the Chemistry Achieve homework #2, question #8
The question reads: NH3 is a weak base ( Kb=1.8×10−5 ) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.073 M in NH4Cl at 25 °C?
The hint is: Cl− is a spectator ion in this situation. Start by finding the Ka of NH4+.

[Michelle Zhang 1J]

Cl- is a spectator ion since it is not involved in the reaction. It is present in the solution but does not react with the other reactants. This is because it is a conjugate base of a strong acid, making it super weak and therefore not have much effect when dissolved in water. It is in the solution in the same amount before and after the reaction.

[Kendall Brown]

The way my TA explained it was that the spectator ion doesn't undergo any changes in the reaction and is just present on both sides.

[Jason Ho 2L]

Spectator ions don't really have a role except being there due to being attached to another ion that does undergo a reaction. As spectator ions don't undergo any reaction, you wouldn't need to include them in the chemical equation.

[Alexander Moroz 1B]

Spectator ions are ions that do not affect the reaction and cancel out. For example, in the equilibrium unit Cl- did not affect the pH of the reaction or concentrations of the products or reactants by itself. However, it was needed in the form of HCl, which dissociated and ultimately increased the h3O+ concentration in the environment.

[Caitlin Gee 2K]

Spectator ions don't affect the reaction because it stays the same on both sides of the reaction. For this reason, we don't include it in calculations.

[daniellediem1k]

spectator ions don't really play a role in a reaction since they cancel out due to them being on both sides of the equation.

[loganchun]

Spectator ions don't have an effect on the reaction and doesn't go through any changes. Because of this, you can just ignore them when you do your calculations. They will cancel each other due to the fact that the spectator ion is on both sides of the equation.

[austinchun]

Spectator ions don't play a role in the chemical equation/reaction. This is because the spectator ions are present on both sides of the equation and would therefore, cancel out.

[Kailin Mimaki 2K]

Spectator ions are never included when writing out the reaction for a calculation. They do not affect the pH, so there is no need to keep them in the equation. Hope this helped!