AP Chemistry Unit 8 Practice Test 2025 Acids and Bases

Last Updated on January 14, 2025

AP Chemistry Unit 8 Practice Test 2025 Acids and Bases. These are the sample questions and answers on the Unit 8 Acids and Bases AP Chemistry exam. You can try both Multiple Choice Questions and Answers and Free-Response Questions. This unit is 11–15% of the Advanced Placement (AP) Exam score.

These multiple-choice questions are about the pH, the qualities and properties of acids and bases, and how they interact in chemical reactions.

Table of Contents

AP Chemistry Unit 8 Practice Test

AP Chemistry Unit 8: Acids and Bases

AP Chemistry Practice Test
Unit 8: Acids and Bases
Total Items: 25 (Multiple Choice Questions)

Unit 8: Acids and Bases

You’ll learn more about pH, the qualities and properties of acids and bases, and how they interact in chemical reactions.

Topics may include:

Introduction to acids and bases
pH and pOH of strong acids and bases
Acid-base reactions and buffers
Molecular structure of acids and bases
pH and pK_a
Properties of buffers
pH and solubility

On The Exam

11%–15% of exam score

1 / 24

Which of the following can be made by partially neutralizing an acid?

(A) BaClOH by neutralizing BaCl₂

(B) KOH by neutralizing H2O with K₂Cr₂O7

(D) MgCO₃ by neutralizing H₂CO₃ with Mg(OH)₂

2 / 24

A solution containing HF is titrated with KOH. At the end point of the titration, the solution contains

(A) equal amounts of HF and KOH

(B) KF and H₂O

(D) H₂O, H₊, OH_-, K₊, F_-, and HF

3 / 24

A buffer at pH 5.32 is prepared from a weak acid with a pK_a = 5.15. If 100 mL of this buffer is diluted to 200 mL with distilled water, what is the pH of the dilute solution?

(A) 5.02

(B) 5.32

(D) The identity of the acid is needed to answer the question.

4 / 24

When an equal number of moles of each pair is mixed to make an aqueous solution, which of these solutions can be called a buffer?

(A) Cu(OH)₂ and CuCl₂

(B) KOH and NaHCO₃

(D) Na₂CO₃ and H₂SO₃

5 / 24

Which of the following has the highest pH?

(A) 0.100 M HCl

(B) 0.200 M HC₂ H₃O₂

(D) 0.200 M NaCl

6 / 24

Which of the following CANNOT occur together in solution?

(A)

(B)

(C)

(D)

7 / 24

When 0.250 mol of NaOH are added to 1.00 L of 0.100 M H₃PO₄, the solution will contain

(A)

(B)

(C)

(D)

8 / 24

A buffer with a pH of 10.0 is needed. Which of the following should be used?

(A) Ethanoic acid with a K_a of 1.8 × 10^-5

(B) Ammonia with a K_a of 1.8 × 10^-5

(D) None of the above

9 / 24

pH is equal to pK_a

(A) when [conjugate acid] = [conjugate base]

(B) at the end point of a titration

(D) in the Henderson-Hasselbalch equation

10 / 24

The pH of a 0.125 M solution of a newly synthesized weak base is 10.45. What is the K_b of this base?

(A) 3.5 × 10^-11

(B) 6.4 × 10^-7

(D) 2.3 × 10^-3

11 / 24

Which of the following is the acid anhydride of a monoprotic acid?

(A) CaO

(B) SO₃

(D) CO₂

12 / 24

Which of the following solutions is expected to result in a solution with the lowest pH? Assume a 0.025 M solution of the nitrate salt of each of these ions.

(A) Ca²⁺

(B) Ni²⁺

(D) Na⁺

13 / 24

Which of the following statements is correct?

(A) HClO₂ is a stronger acid than HClO₃.

(B) HI is a weaker acid than HCl.

(D) HNO₃ is a stronger acid than HNO₂.

14 / 24

What is the pH of a 0.100 M solution of KH2PO4? (For H₃PO₄, pK₁ = 2.15; pK₂ = 7.20; pK₃ = 12.35.)

(A) 9.78

(B) 6.67

(D) 2.15

15 / 24

Which of the following is the correct method for preparing a buffer solution?

(A) Mix the correct amounts of a weak acid and its conjugate base.

(B) Neutralize a weak base partially with strong acid.

(D) All of the above methods may be used to prepare buffers.

16 / 24

Use the titration curve below to answer questions 16 to 21.

What is the titrant and what is the analyte in the experiment that resulted in the titration curve?

(A) The titrant is a strong acid, and the analyte is a strong base.

(B) The titrant is a weak base, and the analyte is a weak acid.

(D) The titrant is a strong acid, and the analyte is a weak base.

17 / 24

Use the titration curve below to answer questions 16 to 21.

What is the pH and volume of titrant at the end point?

(A) pH = 7.00; end point = 25.0 mL

(B) pH = 7.0; end point = 12.5 mL

(D) pH = 5; end point = 25 mL

18 / 24

Use the titration curve below to answer questions 16 to 21.

At which point(s) does the analyte flask contain a buffer solution?

(A) At points 2, 3, 4, and 5

(B) At points 2, 3, 4, 5, and 6

(D) Only at point 7

19 / 24

Use the titration curve below to answer questions 16 to 21.

How many moles of analyte were in the analyte flask if the molarity of the titrant was predetermined to be 0.0855 M?

(A) 2.34 mol

(B) 2.13 mol

(D) 0.0021 mol

20 / 24

Use the titration curve below to answer questions 16 to 21.

What is true about the the pK of the analyte?

(A) pK_a = 9.2

(B) pK_b = 9.2

(D) pK_a = 11.7

21 / 24

Use the titration curve below to answer questions 16 to 21.

What is characteristic of the end point for this type of experiment?

(A) It occurs when a color change occurs.

(B) It occurs at the inflection point of the curve.

(D) It occurs at exactly pH 7.

22 / 24

What is a primary standard used for?

(A) It is used to calibrate a pH meter.

(B) It is used to prepare calibration curves for spectroscopy.

(D) It is the first standard that is prepared.

23 / 24

If 50.0 mL of a 0.0134 M HCl solution is mixed with 24.0 mL of a 0.0250 M NaOH solution, what is the pH of the final mixture?

(A) 1.87

(B) 3.02

(D) 12.40

24 / 24

If 50.0 g of formic acid (HCHO₂, K_a = 1.8 × 10^–4) and 30.0 g of sodium formate (NaCHO₂) are dissolved to make 500 mL of solution, the pH of this solution is

(A) 4.76

(B) 4.12

(D) 3.35

Your score is

Free-Response Questions

Propanoic acid, CH₃CH₂COOH, has an acid ionization constant of K_a = 1.3 × 10^–5. Ammonia, NH₃, has a base ionization constant of Kb = 1.8 × 10^–5.

(a) Write the balanced equation for the reaction of propanoic acid, CH₃CH₂COOH, with ammonia.
(b) Identify the two conjugate acid–base pairs.
(c) Does the equilibrium position lie on the reactant or the product side of the equation when equal moles of propanoic acid and ammonia are mixed? Justify your choice.
(d) Of the two acids in your equation, which is stronger and why?
(e) Of the two bases in your equation, which is stronger and why?
(f) Using appropriate scientific reasoning, state why you would conclude that one binary acid is stronger than another. Give a relevant example.
(g) Using appropriate scientific reasoning, state why you would conclude that one oxoacid is stronger than another. Give a relevant example.