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 0.05 mol/L solution of hydrochloric acid (HCl), a strong acid.

c = 0.05 mol/L
pH =
2.Easy
02468101214acidicneutralbasicpH 3.2

A solution has a pH of 3.2. Find the hydronium ion concentration [H₃O⁺] in mol/L.

pH = 3.2
[H₃O⁺] = mol/L
3.Medium
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.2 mol/L solution of lactic acid (Ka = 0.00014).

c = 0.2 mol/LKa = 0.00014
pH =
4.Medium
02468101214acidicneutralbasicpH = ?

Find the pH pH of a 0.5 mol/L solution of hydrofluoric acid (Ka = 0.00068).

c = 0.5 mol/LKa = 0.00068
pH =
5.Hard
02468101214acidicneutralbasicpH = ?

A buffer contains 0.5 mol/L lactic acid and 0.15 mol/L of its sodium salt. Ka = 0.00014. Find the pH pH of the buffer.

[HA] = 0.5[A⁻] = 0.15Ka = 0.00014
pH =
6.Hard
02468101214acidicneutralbasicpH = ?

A 1.00 L buffer contains 0.3 mol benzoic acid and 0.15 mol of its conjugate base (Ka = 6.3 × 10⁻⁵). 0.01 mol of NaOH is added. Find the new pH pH.

n(HA) = 0.3 moln(A⁻) = 0.15 moln(OH⁻) = 0.01 molKa = 6.3 × 10⁻⁵
pH =

Answer key

  1. 1. pH = 1.301
  2. 2. [H₃O⁺] = 0.000631 mol/L
  3. 3. pH = 2.282
  4. 4. pH = 1.742
  5. 5. pH = 3.331
  6. 6. pH = 3.942

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