AP Chemistry Practice Quiz: Introduction to Acids and Bases
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 11 questions to check your progress.
Question 1 of 11
All Questions (11)
A) log[H3O+]
B) -log[OH-]
C) -log[H3O+]
D) log[OH-]
Correct Answer: C
The provided content explicitly states that pH is calculated as pH = -log[H3O+]. The term pOH is defined as -log[OH-].
A) 1.0
B) 5.0
C) 9.0
D) 14.0
Correct Answer: B
Using the formula pH = -log[H3O+], the calculation is pH = -log(1.0 x 10^-5), which equals 5.0.
A) The concentration of [H3O+] is greater than the concentration of [OH-].
B) The pH is 7.0 and the pOH is 7.0.
C) The value of Kw is 1.0 x 10^-7.
D) The solution is slightly acidic due to the autoionization of water.
Correct Answer: B
The content states that in pure water at 25°C, pH = pOH, which is a neutral solution. At this temperature, pKw = 14.0, so both pH and pOH are equal to 7.0.
A) 1.0 x 10^-14 M
B) 1.0 x 10^-8 M
C) 1.0 x 10^-7 M
D) 1.0 x 10^-6 M
Correct Answer: D
At 25°C, the ion-product constant for water is Kw = [H3O+][OH−] = 1.0 x 10^-14. To find [H3O+], rearrange the equation: [H3O+] = Kw / [OH-] = (1.0 x 10^-14) / (1.0 x 10^-8) = 1.0 x 10^-6 M.
A) 3.0
B) 7.0
C) 11.0
D) 14.0
Correct Answer: A
At 25°C, the relationship between pH and pOH is pH + pOH = 14.0. Therefore, pH = 14.0 - pOH = 14.0 - 11.0 = 3.0.
A) The pH will decrease, and the water will become acidic.
B) The pH will increase, but the water will remain neutral.
C) The pH will remain 7.0 because the water is pure.
D) The value of Kw will increase.
Correct Answer: B
Since autoionization is endothermic, decreasing the temperature shifts the equilibrium to the left, decreasing both [H3O+] and [OH-]. A lower [H3O+] results in a higher pH (pH = -log[H3O+]). Because it is pure water, [H3O+] still equals [OH-], so the solution remains neutral, but its pH will be greater than 7.0.
A) [H3O+] / [OH-]
B) pH + pOH
C) [H3O+][OH-]
D) -log([H3O+][OH-])
Correct Answer: C
The provided content defines the equilibrium constant for the autoionization of water as Kw = [H3O+][OH−].
A) The pH is exactly 7.0.
B) The sum of pH and pOH is exactly 14.0.
C) The concentration of H3O+ is equal to the concentration of OH-.
D) The concentration of H3O+ is 1.0 x 10^-7 M.
Correct Answer: C
The definition of a neutral solution is one where the concentration of hydronium ions equals the concentration of hydroxide ions ([H3O+] = [OH-]). The values pH=7 and pH+pOH=14 are only true at 25°C, as Kw is temperature dependent.
A) 4.0
B) 7.0
C) 10.0
D) 14.0
Correct Answer: C
First, calculate the pOH: pOH = -log[OH-] = -log(1.0 x 10^-4) = 4.0. Then, use the relationship for 25°C: pH + pOH = 14.0. So, pH = 14.0 - 4.0 = 10.0.
A) 7.26
B) 7.00
C) 6.63
D) 13.26
Correct Answer: C
In a neutral solution, [H3O+] = [OH-]. Therefore, Kw = [H3O+]^2. To find [H3O+], take the square root of Kw: [H3O+] = √(5.5 x 10^-14) ≈ 2.34 x 10^-7 M. Then, calculate the pH: pH = -log(2.34 x 10^-7) ≈ 6.63. This shows how the pH of neutral water deviates from 7.0 at temperatures other than 25°C.
A) Hydroxide ion
B) Hydronium ion
C) Water molecule
D) Hydrogen peroxide
Correct Answer: B
The content explicitly states that [H3O+] represents the hydronium ion concentration and that H3O+ and H+ are used interchangeably to represent the acidic proton in aqueous solution.