HA(aq)+ H2O (l) <-> H3O+(aq)+ A¯ (aq)
Given the reaction above, which of the following will cause an increase in the pH of an equilibrium mixture? Give all answers which apply.
A) add KA B) add HA
C) remove A¯ D) remove HA
E) none of these will affect the pH.
There are Le Chatelier's Principle type question. You want answers that will shift the equilibrium to the left since that will decrease the H^+ (thus the pH will go up)
To determine which of the given options will cause an increase in the pH of an equilibrium mixture, we need to understand the effect of each option on the concentration of H3O+ ions.
In the given equilibrium reaction: HA(aq) + H2O(l) ↔ H3O+(aq) + A¯(aq), the H3O+ ions represent the concentration of hydronium ions or acidity in the solution.
Let's analyze each option:
A) Add KA:
Adding KA does not directly affect the concentration of H3O+ ions in the equilibrium mixture. KA represents the conjugate base of the acid, so adding it will not directly impact the concentration of H3O+ ions.
B) Add HA:
Adding HA, which is the acid in the reaction, will increase the concentration of H3O+ ions in the equilibrium mixture. This is because adding more acid will shift the equilibrium to the right, producing more H3O+ ions.
C) Remove A¯:
Removing the conjugate base (A¯) from the mixture will also indirectly increase the concentration of H3O+ ions. Removing A¯ will shift the equilibrium to the left, resulting in the formation of more H3O+ ions to restore balance.
D) Remove HA:
Removing HA, which is the acid, will decrease the concentration of H3O+ ions in the mixture. By removing the acid, the equilibrium will shift to the left, reducing the concentration of H3O+ ions.
E) None of these will affect the pH:
This option is not correct since option B and C will indeed affect the pH of the equilibrium mixture.
In conclusion, adding HA (option B) and removing A¯ (option C) are the options that will cause an increase in the pH of an equilibrium mixture.