All Flashcards
What is a buffer solution?
A solution that resists changes in pH upon addition of small amounts of acid or base.
Define a weak acid.
An acid that only partially dissociates into its ions in a solution.
Define a conjugate base.
The species that remains after an acid has donated a proton.
What is maximum buffer capacity?
The point where a buffer resists pH changes the best, occurring when [weak acid] = [conjugate base].
Define buffer effectiveness.
How well a buffer resists changes in pH.
What is a spectator ion?
An ion that exists in the same form on both the reactant and product sides of a chemical reaction. It does not affect equilibrium.
How does a buffer neutralize added acid (H+)?
The conjugate base (A-) reacts with H+ to form the weak acid (HA), preventing a large increase in [H+].
How does a buffer neutralize added base (OH-)?
The weak acid (HA) reacts with OH- to form the conjugate base (A-) and water (H2O), preventing a large increase in [OH-].
What are the steps to preparing a buffer solution?
- Choose a weak acid/base system with a pKa close to the desired pH. 2. Mix the weak acid/base with its conjugate in comparable concentrations. 3. Adjust the pH with strong acid or base, if necessary.
What is the effect of adding a strong acid to a buffer solution?
The conjugate base in the buffer reacts with the added acid, minimizing the change in pH.
What is the effect of adding a strong base to a buffer solution?
The weak acid in the buffer reacts with the added base, minimizing the change in pH.
What happens if the concentrations of a weak acid and its conjugate base are not comparable in a solution?
The buffer will have a limited capacity to resist pH changes, especially if a strong acid or base is added that exceeds the concentration of the limiting component.
What is the effect of [weak acid] = [conjugate base]?
The buffer is at its maximum buffer capacity.