Define a buffer solution.
A mixture of a weak acid (HA) and its conjugate base (A-) that resists drastic changes in pH.
What is a weak acid?
An acid that does not fully dissociate into its ions when dissolved in water.
What is a conjugate base?
The species that remains after an acid has donated a proton.
Define spectator ions.
Ions that do not participate in a reaction and remain unchanged in solution.
What is the Henderson-Hasselbalch equation used for?
Calculating the pH of a buffer solution, given the pKa of the weak acid and the ratio of the concentrations of the conjugate base and weak acid.
Define the term 'equivalence point' in a titration.
The point in a titration where the amount of titrant added is stoichiometrically equivalent to the amount of analyte present.
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 to the pH at the half-equivalence point?
The pH is equal to the pKa of the weak acid.
What happens if you add too much strong acid to a buffer, exceeding its buffering capacity?
The pH will drastically decrease, as the buffer can no longer effectively neutralize the added acid.
What happens to the pH at the equivalence point in a weak acid-strong base titration?
The pH will be greater than 7 due to the formation of the conjugate base, which hydrolyzes to produce hydroxide ions.
What are the key differences between strong acid-strong base and weak acid-strong base reactions?
Strong Acid-Strong Base: Strong acids and bases fully dissociate; spectator ions are present. Weak Acid-Strong Base: Weak acid does not fully dissociate; conjugate base affects pH; buffer region exists.
Compare and contrast pH and pOH.
pH: Measures the acidity of a solution; pH = -log[H+]. pOH: Measures the basicity of a solution; pOH = -log[OH-]. Both are related by the equation pH + pOH = 14 at 25°C.
Differentiate between Ka and pKa.
Ka: Acid dissociation constant; measures the strength of an acid. pKa: -log(Ka); lower pKa indicates a stronger acid.
Contrast the equivalence point and the half-equivalence point in a titration.
Equivalence Point: The point where the acid and base have completely reacted. Half-Equivalence Point: The point where exactly half of the acid has been neutralized, and pH = pKa.
