Standardization of Acids and Bases

PHENOLPHTHALEIN SOLUTION - Dissolve 0.5 g phenolphthalein in 85 mL 95% ethanol and dilute to 100 mL with deionized H20.

Standardization of Na0H

  1. Accurately weigh out three 0.2300 to 0.2500 g portions of KHP (Potassium Hydrogen Phthalate) on weighing paper and quantitatively transfer to three 250 mL Erlenmeyer flasks. (KHP must be dry; dry in oven before weighing and cool in desiccator before using.)
  2. Add 50 mL deionized water and dissolve by stirring.
  3. Add 3 drops of phenolphthalein solution.
  4. Titrate with unknown NaOH solution (approximately 0.05 M) to endpoint (very faint persistent pink).


  1. # equivalents KHP = wt. KHP - 204.23 g/eq.
  2. N NaOH = (# equivalents KHP)/(mL NaOH)(0.001)

Standardization of H2SO4

  1. Pipet 20 mL standardized Na0H into four 150 mL beakers.
  2. Add 3 drops of phenolphthalein solution.
  3. Titrate with unknown H2SO4 solution to endpoint.


  1. N H2SO4 = (N NaOH x mL NaOH)/mL H2SO4
    (Take out the high and low numbers and average middle two. If there is too much discrepancy, try again.)


  1. Peters, D. G., J. M. Hayes, and G. M. Hieftje. 1976. A Brief Introduction to Modern Chemical Analysis, p.87-118. W. B. Sanders Company, Philadelphia.