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Strong Acids - pH of HCl


Concentrated solutions of HCl are corrosive and toxic.

Chemicals and Solutions

  • 0.1 M HCl
  • Methyl orange indicator solution


  • 5 cylinders
  • 100 ml graduated cylinder
  • 10 ml grad. cylinder
  • Buffer array of methyl orange indicator
  • Stir rods
  • pH meter and digital display


  1. Mark cylinders as follows: 0.1 M, 0.01 M, 10-3 M, 10-4 M, 10-5 M Hydrochloric acid.
  2. Fill the first cylinder (marked 0.1 M) with 100 ml of 0.1 M HCl.
  3. Measure 10 ml of 0.1 M HCl into 100 ml cylinder, dilute to 100 ml with distilled water.
  4. Repeat the above step, making a serial dilution, until all the concentrations have been made.
  5. Add methyl orange indicator to each concentration and compare color to the buffer array. Use the pH meter-digital display to take the pH of each concentration.

Hint: This demonstration can be used in conjunction with demonstration Weak Acids - pH of Acetic Acid.