Chemistry · Unit 8 · Paper 3

Acids & Bases unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 20 terms and is the same for everyone, so a teacher can assign “Unit 8, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 37 min 34 points0/17 attempted

Henderson-Hasselbalch equation

Titration curve of a weak acid

Brønsted-Lowry definition

Structure and acid strength

Strong vs weak acids

pH, pOH and their relationship

Autoionization of water

Buffer capacity

Amphoteric species

Salt hydrolysis

Why pH = pKa at half-equivalence

Relationship of Ka and Kb

Short answer 1. Define or explain: Ka and acid strength

3 pts

Short answer 2. Define or explain: Percent ionization

3 pts

Short answer 3. Define or explain: Choosing an indicator

3 pts

Short answer 4. Define or explain: Titration curve features to label

3 pts

Free response

10 pts

A 0.500 L buffer solution contains 0.20 M acetic acid (CH₃COOH, Ka = 1.8 × 10⁻⁵) and 0.20 M sodium acetate (CH₃COONa).

Calculate the pH of the buffer.

Calculate the pH after 0.010 mol of solid NaOH is added. Assume no change in volume.

Explain why this solution resists changes in pH.

Identify which component of the buffer reacts with added HCl.