Compare the pH of solutions of hydrochloric acid and acetic acid having same concentration.

Chemistry Lab ManualNCERT Solutions Class 11 Chemistry Sample Papers

Requirements

Test tubes, glass rod, universal indicator solution, 0.1 M HCl, 0.01 M HCl,  0.1 M  CH3COOH  and 0.01 M  CH3COOH.

Theory

A strong acid is completely ionised in aqueous solution. It produces higher conccentration of hydrogen ions for a given concentration of the acid as compared with a weak acid and hence has lower pH.

Procedure

1. Take four clean and dry test tubes and half fill each of the tubes with one of the acid solutions.
2. Add 3-4 drops of universal indicator to each test tube and swirl the solutions until the colours are uniform.
3. Compare the colour of each solution with the ‘pH indicator chart’ and estimate the pH of each solution and record the observations in the data table.

Observations And Results

Solution Colour produced in the solution

by universal indicator

Approximate pH
0.1 M HCl

0.1 M CH3COOH

0.01 M HCl

0.01 M CH3COOH

Conclusion

The pH of a solution of HCl (a strong acid) is lower than the pH of a solution of CH3COOH (a weak acid) having same concentration.