High School Chemistry  ·  Practice by Skill

Acids and Bases Practice Problems

Acid and base problems are about hydrogen ion concentration and how the pH scale measures it. Strong acids ionize completely, weak acids only partly, and that difference decides which method you use. Practice below covers pH calculations, Brønsted-Lowry acids and bases, buffers, and neutralization.

What you’ll practice

  • pH and pOH: convert between concentration, pH, and pOH.
  • Strong and weak acids and bases: decide when to assume complete ionization and when to use Ka or Kb.
  • Brønsted-Lowry theory: identify acids, bases, and conjugate pairs in a reaction.
  • Buffers and titrations: reason about buffer pH and what happens at the endpoint of a neutralization.

Learn the method first →

A quick example: pH of a strong base

What is the pH of 0.0010 M NaOH? NaOH is a strong base, so [OH−] = 0.0010 M.

pOH = −log(0.0010) = 3.00, and pH + pOH = 14.

So pH = 14.00 − 3.00 = 11.00.

3 free acids and bases problems

Give each one a real try before you open the solution. Your answer is checked as soon as you submit it, and the worked solution shows every step so you can see exactly where a setup went wrong.

#1Strong Acid pH
Calculate the pH of a 0.010 M HCl solution. (HCl is a strong acid — it ionizes completely.)
#2Brønsted-Lowry Acid
In the reaction NH4+ + H2O ⇌ NH3 + H3O+, which species is the Brønsted-Lowry acid?
#3Mass → Molarity → pH
0.365 g of HCl (molar mass = 36.46 g/mol) is dissolved in enough water to make 500.0 mL of solution. Calculate the pH of the resulting solution.

Questions you might have about acids and bases

How do I calculate pH?
For a strong acid, the hydrogen ion concentration equals the acid concentration, and pH = −log[H+]. A 0.010 M HCl solution has pH 2.00.
What is the difference between a strong and a weak acid?
A strong acid ionizes completely in water, while a weak acid ionizes only slightly and reaches an equilibrium described by Ka. A weak acid at the same concentration has a higher pH than a strong one.
What is a buffer?
A buffer is a mix of a weak acid and its conjugate base that resists changes in pH when small amounts of acid or base are added. The acid neutralizes added base, and the conjugate base neutralizes added acid.
What is the endpoint of a titration?
The endpoint is the point where the indicator changes color to show the acid and base have reacted in equal mole amounts. For a strong acid and strong base the solution is neutral, pH 7, at that point.
High School Chemistry · Acids and Bases Practice Problems