AP Chemistry Flashcards: pH and pOH of Strong Acids and Bases
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
For a strong acid like HCl, what is the relationship between its initial concentration and the resulting hydronium ion concentration, [H3O+]?
The hydronium ion concentration, [H3O+], is equal to the initial concentration of the strong acid because it ionizes completely in solution.
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For a strong acid like HCl, what is the relationship between its initial concentration and the resulting hydronium ion concentration, [H3O+]?
The hydronium ion concentration, [H3O+], is equal to the initial concentration of the strong acid because it ionizes completely in solution.
Calculate the pOH of a 0.10 M solution of NaOH (a Group I hydroxide).
Since NaOH is a strong base, [OH-] equals the initial concentration of 0.10 M. The pOH is -log(0.10), which is 1.00.
What defines a strong acid in an aqueous solution?
A strong acid is an acid that completely ionizes in an aqueous solution, meaning the concentration of H3O+ ions is equal to the initial acid concentration.
What is characteristic of strong bases, such as Group I and II hydroxides, in solution?
Strong bases are characterized by their complete dissociation in solution, yielding a concentration of hydroxide ions (OH-) directly related to the initial base concentration.
What is the hydroxide ion concentration, [OH-], in a 0.020 M solution of Ba(OH)2?
Ba(OH)2 is a Group II hydroxide, so the [OH-] is twice the initial concentration. Therefore, [OH-] = 2 * 0.020 M = 0.040 M.
List three of the six common strong acids mentioned that completely ionize in water.
Any three from this list are correct: HCl, HBr, HI, HClO4, H2SO4, or HNO3.
Calculate the pH of a 0.010 M solution of nitric acid (HNO3).
Since HNO3 is a strong acid, [H3O+] = 0.010 M. The pH is calculated as -log(0.010), which equals 2.00.
Calculate the pH of a 0.0050 M solution of Ca(OH)2.
First, find [OH-] which is 2 * 0.0050 M = 0.010 M. The pOH is -log(0.010) = 2.00, so the pH is 14.00 - 2.00 = 12.00.
Why is the hydroxide ion concentration [OH-] double the initial molarity for a Group II hydroxide like Ca(OH)2?
The [OH-] is doubled because each formula unit of a Group II hydroxide, like Ca(OH)2, completely dissociates to release two hydroxide ions into the solution.
A solution of the strong acid HBr has a pH of 1. What was the initial concentration of the HBr?
The [H3O+] is 10^-pH, so [H3O+] = 10^-1 = 0.1 M. Because HBr is a strong acid that ionizes completely, the initial [HBr] was also 0.1 M.