All Flashcards
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.
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.
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.