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Define pH.
pH = -log[H+], a measure of the acidity or basicity of a solution.
Define pKa.
pKa = -log(Ka), a measure of acid strength; lower pKa indicates a stronger acid.
Define pOH.
pOH = -log[OH-], a measure of the hydroxide ion concentration in a solution.
Define Ka.
Acid dissociation constant, a measure of the strength of an acid in solution.
Define Buffer.
A solution that resists changes in pH when small amounts of acid or base are added. Consists of a weak acid and its conjugate base.
Define Equivalence Point.
The point in a titration where the amount of titrant added is stoichiometrically equivalent to the amount of analyte being titrated.
Define Acid-Base Indicator.
A substance that changes color depending on the pH of the solution, used to signal the endpoint of a titration.
What are the key differences between pH and pKa?
pH: Measures the acidity/basicity of a solution. | pKa: Measures the strength of an acid.
Compare strong acids and weak acids in terms of pKa.
Strong acids: Have very low or negative pKa values. | Weak acids: Have higher pKa values.
Differentiate between Ka and pKa.
Ka: Acid dissociation constant (linear scale). | pKa: -log(Ka) (logarithmic scale).
Compare the pH at the half-equivalence point and the equivalence point in a weak acid titration.
Half-equivalence point: pH = pKa of the weak acid. | Equivalence point: pH depends on the conjugate base hydrolysis and is usually > 7.
Compare the effective range of an indicator and its pKa.
Effective Range: The pH range where the indicator changes color (pKa ± 1). | pKa: The pH at which the indicator is exactly halfway between its two colors.
What is the effect of decreasing the pKa value of an acid?
The acid becomes stronger.
What is the effect of adding a strong acid to a buffer solution?
The buffer resists drastic pH change by reacting with the added acid.
What happens when [A-] = [HA] in a buffer solution?
pH = pKa, and the buffer is at its strongest.
What happens if you choose an indicator with a pKa far from the equivalence point?
The endpoint of the titration will not accurately reflect the equivalence point.
What is the effect of diluting a buffer solution?
The pH remains relatively constant, but the buffer capacity decreases.
What happens to the pH of a solution as the concentration of H+ ions increases?
The pH decreases.