All Flashcards
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.
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 steps to calculate the pH after adding a strong base to a strong acid?
- Write the balanced chemical equation. 2. Write the net ionic equation. 3. Calculate millimoles of acid and base. 4. Determine the limiting reactant. 5. Calculate the concentration of excess H+ or OH-. 6. Calculate pH or pOH.
What are the steps to calculate the pH after adding a strong base to a weak acid?
- Write the balanced chemical equation. 2. Write the net ionic equation. 3. Calculate millimoles of acid and base. 4. Use stoichiometry to determine the amounts of weak acid and conjugate base formed. 5. Use the Henderson-Hasselbalch equation to calculate the pH.
Describe the steps to determine the pH at the half-equivalence point.
- Recognize that at the half-equivalence point, [HA] = [A-]. 2. Understand that pH = pKa at this point. 3. Find the pKa value (-log(Ka)). 4. pH = pKa.
Outline the process for calculating the pH at the equivalence point of a weak acid-strong base titration.
- Determine the volume of NaOH needed to reach the equivalence point. 2. Calculate the concentration of the conjugate base formed. 3. Set up an ICE table for the hydrolysis of the conjugate base. 4. Calculate Kb. 5. Calculate [OH-]. 6. Calculate pOH. 7. Calculate pH.