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.
Answer A and D ??
I agree.
To determine which of the given options will cause an increase in the pH of an equilibrium mixture, you need to consider the effect of each option on the concentration of hydronium ion (H3O+), which determines the acidity or basicity of a solution.
A) Adding KA: The addition of KA (potassium acetate) would increase the concentration of the acetate ion (A¯). According to Le Chatelier's principle, adding more of the product (A¯) would shift the equilibrium towards the reactants (HA and H2O). As a result, the concentration of hydronium ions (H3O+) would decrease, leading to an increase in pH. Therefore, this option will cause an increase in the pH.
B) Adding HA: Adding more of HA (acetic acid) to the equilibrium mixture would introduce additional hydronium ions (H3O+). According to Le Chatelier's principle, increasing the concentration of a reactant would shift the equilibrium towards the products (A¯ and H3O+). This would cause an increase in the concentration of H3O+ ions, resulting in a decrease in pH rather than an increase. Therefore, this option does not cause an increase in the pH.
C) Removing A¯: Removing A¯ (acetate ion) from the equilibrium mixture would cause a shift towards the products side. This shift would lead to a decrease in the concentration of HA and H3O+ ions, resulting in an increase in pH. Therefore, removing A¯ would cause an increase in the pH.
D) Removing HA: Removing HA (acetic acid) from the equilibrium mixture would cause a shift towards the reactants side. This shift would lead to a decrease in the concentration of H3O+ ions, resulting in an increase in pH. Therefore, removing HA would cause an increase in the pH.
E) This option states that none of the given options will affect the pH. However, as explained above, options A, C, and D would cause an increase in the pH.
Therefore, the correct answers are A) add KA and D) remove HA.