All Flashcards
Define a buffer solution.
A solution that resists changes in pH, consisting of a weak acid and its conjugate base (or a weak base and its conjugate acid).
Define pH.
A measure of acidity, calculated as -log[H+].
Define pKa.
-log(Ka), which indicates the acid's strength. A lower pKa means a stronger acid.
Define Ka.
The acid dissociation constant, a measure of the strength of an acid in solution.
What is the conjugate base?
The species formed when an acid donates a proton (H+).
Difference between Ka and pKa.
Ka: Acid dissociation constant, measures acid strength (higher = stronger). pKa: -log(Ka), also measures acid strength (lower = stronger).
Difference between a strong acid and a weak acid in the context of buffers.
Strong Acid: Completely dissociates in solution, not suitable for buffers. Weak Acid: Partially dissociates, forms a buffer with its conjugate base.
Difference between using molarity and moles in the Henderson-Hasselbalch equation.
Molarity: Can be used if the volumes of the acid and conjugate base solutions are the same, so the volume cancels out in the ratio. Moles: Can always be used, regardless of volume, as the ratio is what matters.
Difference between equivalence point and half-equivalence point in a titration.
Equivalence Point: Moles of acid = moles of base. Half-Equivalence Point: Moles of acid = moles of conjugate base, pH = pKa.
Difference between acid and conjugate base.
Acid: Donates a proton (H+). Conjugate Base: Accepts a proton (H+).
What is the effect of adding a strong acid to a buffer solution?
The conjugate base in the buffer reacts with the added acid, neutralizing it and 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, neutralizing it and minimizing the change in pH.
What is the effect of diluting a buffer solution?
The pH of the buffer remains relatively constant, as the ratio of [A-]/[HA] does not change significantly.
What happens when [A-] = [HA]?
The log term in the Henderson-Hasselbalch equation becomes zero, and pH = pKa, resulting in the strongest buffer action.
What happens when the concentrations of the acid or base exceed the buffer capacity?
The buffer's ability to resist pH changes is overwhelmed, and the pH changes significantly.