pH & buffers worksheet with answers

Free printable pH & buffers worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.004 mol/L solution of NaOH, a strong base, at 25 °C.

c = 0.004 mol/L
pH =
2.Easy
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.25 mol/L solution of hydrochloric acid (HCl), a strong acid.

c = 0.25 mol/L
pH =
3.Medium
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.5 mol/L solution of benzoic acid (Ka = 6.3 × 10⁻⁵).

c = 0.5 mol/LKa = 6.3 × 10⁻⁵
pH =
4.Medium
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.05 mol/L solution of lactic acid (Ka = 0.00014).

c = 0.05 mol/LKa = 0.00014
pH =
5.Hard
02468101214acidicneutralbasicpH = ?

A 1.00 L buffer contains 0.3 mol benzoic acid and 0.2 mol of its conjugate base (Ka = 6.3 × 10⁻⁵). 0.05 mol of NaOH is added. Find the new pH pH.

n(HA) = 0.3 moln(A⁻) = 0.2 moln(OH⁻) = 0.05 molKa = 6.3 × 10⁻⁵
pH =
6.Hard
02468101214acidicneutralbasicpH = ?

A buffer contains 0.5 mol/L hypochlorous acid and 0.2 mol/L of its sodium salt. Ka = 3 × 10⁻⁸. Find the pH pH of the buffer.

[HA] = 0.5[A⁻] = 0.2Ka = 3 × 10⁻⁸
pH =

Answer key

  1. 1. pH = 11.6
  2. 2. pH = 0.6021
  3. 3. pH = 2.253
  4. 4. pH = 2.589
  5. 5. pH = 4.201
  6. 6. pH = 7.125

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