8 original questions from New Regents. The worksheet, answer key, and browser practice are free.
Acid and Base Particle Models 4 questions
Acid and Base Particle Models
New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.
Use H3O+ for hydronium and OH- for hydroxide. An acidic aqueous solution has a greater concentration of H3O+ than of OH-.
Question 1
When an acid HA transfers a proton to H₂O, which ion forms from H₂O?
- OH⁻
- H₃O⁺
- O²⁻
- H₂⁺
Question 2
Water reacts with ammonia according to NH₃ + H₂O ⇌ NH₄⁺ + OH⁻. Explain why NH₃ acts as a base.
Write your answer and work on the printable worksheet, or answer online.
Question 3
In a neutral water sample, how do the concentrations of H₃O⁺ and OH⁻ compare?
- Both must be exactly zero.
- H₃O⁺ is greater.
- OH⁻ is greater.
- They are equal.
Question 4
Two equal-volume samples start with equal amounts of monoprotic acid. Acid X ionizes almost completely. Acid Y ionizes only slightly. Identify the stronger acid and explain.
Write your answer and work on the printable worksheet, or answer online.
Counting Ions in Water Models 4 questions
Counting Ions in Water Models
Use the information below to answer the questions.
The models show relative ion counts in equal volumes at the same temperature. Water molecules and counterions are omitted. The counts are simplified for comparison.
| Model | H3O+ count | OH- count |
|---|---|---|
| P | 18 | 2 |
| Q | 6 | 6 |
| R | 2 | 18 |
Question 5
Which model represents a basic sample?
- P
- Q
- R
- P and Q
Question 6
How many times as great is the hydronium concentration in P as in R? Use the counts and explain why volume matters.
Write your answer and work on the printable worksheet, or answer online.
Question 7
What can be concluded from model Q?
- It represents an acidic sample.
- It represents a basic sample.
- It represents a neutral sample.
- It contains no ions.
Question 8
Model P represents an acidic sample. Explain why its hydronium count alone cannot determine whether the acid used to make it was strong or weak.
Write your answer and work on the printable worksheet, or answer online.
2025 Chemistry Reference Tables · Browse Chemistry worksheets