AP Chem Henderson-Hasselbalch equation practice questions
Practice questions and flashcards to master the Henderson-Hasselbalch equation for AP Chemistry exam preparation.
Quiz(32 questions)
1. What does the Henderson-Hasselbalch equation help to determine in a buffer solution?
Terms in this Study Set(32)
Henderson-Hasselbalch Basics(16)
What is the Henderson-Hasselbalch equation?
The equation is: pH = pKa + log\frac{[A^-]}{[HA]} where [A^-] is the concentration of the base and [HA] is the concentration of the acid.
Purpose of the Henderson-Hasselbalch equation?
To calculate the pH of a buffer solution based on the concentrations of an acid and its conjugate base.
True or False: The Henderson-Hasselbalch equation only applies to strong acids.
False. It is used for weak acids and their conjugate bases.
Identify components: pKa, [A^-], and [HA].
pKa: acid dissociation constant; [A^-]: concentration of conjugate base; [HA]: concentration of weak acid.
Fill in the blank: The Henderson-Hasselbalch equation is useful in ____________.
buffer solution calculations.
pH vs. pKa: What's the difference?
pH measures acidity; pKa measures acid strength (lower pKa = stronger acid).
How does increasing [A^-] affect pH?
Increasing [A^-] (conjugate base) raises the pH, making the solution less acidic.
Calculate pH if pKa = 4.75, [A^-] = 0.1 M, [HA] = 0.05 M.
pH = 4.75 + log\frac{0.1}{0.05} = 4.75 + 0.301 = 5.05.
What does a buffer solution do?
Resists changes in pH upon addition of small amounts of acid or base.
True or False: Adding strong acid to a buffer drastically changes its pH.
False. Buffers can minimize pH changes when strong acids or bases are added.
Identify a common buffer system.
Acetic acid (CH₃COOH) and sodium acetate (CH₃COONa) is a common buffer.
Effect of dilution on pH of a buffer solution?
Dilution does not significantly affect the pH if the ratio [A^-]/[HA] remains constant.
What happens if [HA] = [A^-]?
If [HA] = [A^-], then pH = pKa.
How does pH change with increased [HA]?
Increasing [HA] lowers the pH, making the solution more acidic.
What is the significance of pKa in buffer solutions?
pKa indicates the pH at which the acid is half dissociated; crucial for buffer effectiveness.
Calculate pH if pKa = 6.1, [A^-] = 0.2 M, [HA] = 0.1 M.
pH = 6.1 + log\frac{0.2}{0.1} = 6.1 + 0.301 = 6.40.
Calculating pH and pKa(16)
What does the Henderson-Hasselbalch equation calculate?
pH of a buffer solution based on concentration of acid and conjugate base.
Fill in the blank: pH = pKa + log(____/____)
base/acid
If pKa = 4.75, what is pH when [A-] = 0.1 M and [HA] = 0.01 M?
pH = 4.75 + log(0.1/0.01) = 4.75 + 1 = 5.75.
True or False: pH increases when the concentration of the conjugate base increases.
True. Increased [A-] raises pH.
Calculate the pH of a buffer: [HA] = 0.2 M, [A-] = 0.1 M, pKa = 5.
pH = 5 + log(0.1/0.2) = 5 - 0.301 = 4.699.
What happens to pH if [HA] increases but [A-] remains constant?
pH decreases because the ratio [A-]/[HA] becomes smaller.
For a buffer containing acetic acid, if pKa = 4.76, what is the pH when [A-] = 0.05 M, [HA] = 0.15 M?
pH = 4.76 + log(0.05/0.15) = 4.76 - 0.176 = 4.584.
Calculate pH: [HA] = 0.3 M, [A-] = 0.7 M, pKa = 4.75.
pH = 4.75 + log(0.7/0.3) = 4.75 + 0.423 = 5.173.
True or False: Increasing [HA] and [A-] by the same factor affects the pH.
False. Ratio remains constant, so pH stays the same.
Calculate pKa if pH = 5.0 and [A-] = 0.5 M, [HA] = 0.25 M.
pH = pKa + log(0.5/0.25) -> pKa = 5.0 - 0.301 = 4.699.
What is the significance of a buffer's pKa?
It indicates the pH at which the buffer is most effective.
If pKa = 7.4, what is the pH when [A-] = 1 M and [HA] = 0.1 M?
pH = 7.4 + log(1/0.1) = 7.4 + 1 = 8.4.
Calculate pH for a weak acid buffer: [HA] = 0.4 M, [A-] = 0.2 M, pKa = 5.1.
pH = 5.1 + log(0.2/0.4) = 5.1 - 0.301 = 4.799.
Fill in the blank: pH = pKa + log([____]/[____])
base/acid
If pH = pKa, what is the ratio of [A-] to [HA]?
The ratio [A-]/[HA] is 1.
What is the effect of dilution on buffer pH?
Dilution doesn't change pH if [HA] and [A-] are diluted equally.
Questions in this Study Set(32)
1. What does the Henderson-Hasselbalch equation help to determine in a buffer solution?
2. What does the Henderson-Hasselbalch equation relate to in a buffer solution?
3. Which of the following statements is true regarding the Henderson-Hasselbalch equation?
4. Fill in the blank: pH = pKa + log(____/____).
5. What happens to the pH if the concentration of the conjugate base increases while the acid concentration remains constant?
6. If pKa is 5.0 and [A-] = 0.2 M and [HA] = 0.02 M, what is the pH?
7. If both [HA] and [A^-] are equal, what is the relationship between pH and pKa?
8. True or False: Increasing the concentration of [A-] always increases the pH.
9. Which of the following is a common example of a buffer system?
10. Calculate the pH for a buffer with [HA] = 0.1 M, [A-] = 0.5 M, and pKa = 4.5.
11. Which of the following correctly describes the role of pKa in buffer solutions?
12. What happens to pH if [HA] is increased while [A-] remains constant?
13. How does dilution affect the pH of a well-buffered solution?
14. For which of the following scenarios is the pH equal to pKa?
15. What would happen to the pH of a buffer if a small amount of strong acid is added?
16. If pKa = 6.0, what is the pH of a buffer with [A-] = 0.4 M and [HA] = 0.1 M?
17. If pKa = 5.0 and the concentrations are [A^-] = 0.1 M and [HA] = 0.2 M, what is the pH?
18. Calculate pKa given pH = 7.0, [A-] = 0.25 M, and [HA] = 0.5 M.
19. Which of the following is NOT a component of the Henderson-Hasselbalch equation?
20. Which of the following describes the effect of dilution on a buffer's pH?
21. What is the effect of increasing the concentration of weak acid [HA] on the pH of the solution?
22. What is the ratio of [A-] to [HA] when the pH is equal to pKa?
23. In a scenario where [A^-] is significantly higher than [HA], what can be inferred about the pH compared to pKa?
24. If pKa is 4.75, which buffer has a pH closest to 5.0?
25. What is the primary function of a buffer solution in a chemical reaction?
26. True or False: A buffer is more effective when its pKa is close to the desired pH.
27. Which of the following correctly represents the Henderson-Hasselbalch equation?
28. Calculate the pH for a weak acid buffer with [HA] = 0.5 M, [A-] = 0.5 M, and pKa = 4.0.
29. If a buffer solution has a pKa of 7.4 and contains equal concentrations of acid and conjugate base, what is the pH?
30. Which of the following statements about the Henderson-Hasselbalch equation is NOT true?
31. What is the primary purpose of using the Henderson-Hasselbalch equation in a chemical context?
32. If you have a buffer solution with a pKa of 5.0 and you add more weak acid [HA] while keeping [A-] constant, what will happen to the pH?
Related Study Sets
Wiederholung: Ionen- und Elektronenpaarbindung
Test: Reaktionsgleichungen ausgleichen
Säuren Basen pH Karteikarten
Wiederholung: Abitur Elektrochemie
Redox Überblick Schritt für Schritt
Abitur Reaktionskinetik Prüfung
Abitur Säuren und Puffer Karteikarten
Periodensystem lesen Schritt für Schritt
Create Your Own Study Set
Upload a PDF, paste your notes, or describe a topic – AI generates flashcards, quizzes and more in seconds.
