Chemicals and Solutions
- 0.1 M Acetic acid
- Methyl orange indicator solution, dropper bottle
Materials
- 5 hydrometer cylinders
- 10 mL grad. cylinder
- 100 ml graduated cylinder
- pH meter and digital display
- buffer array of methyl orange indicator
- stir rods
Procedure
- Mark both sets of cylinders as follows: 10-1M, 10-2M, 10-3 M, 10-4 M, 10-5 M. Be sure to mark both sets of cylinders in this manner.
- Add methyl orange indicator to each concentration of acetic acid and compare the 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 Strong Acids - pH of HCl.
Discussion
Acetic acid solutions with the following concentrations have the pH indicated:
Concentration in M acetic acid |
pH |
0.1 | 2.87 |
0.01 | 3.37 |
0.001 | 3.8 |
0.0001 | 4.3 |
0.00001 |
Vinegar is ~5% acetic acid solution which is ~0.9 M which is ~pH 2.4.