7.03 Lab Ph

Procedure:
Part I: Titration with an Indicator
1. Fill the 50-milliliter buret with a 0.25 molar NaOH solution.
2. Record volume.
3. Measure out between 20 milliliters and 40 milliliters of the unknown HCl solution.
4. Record volume.
5. The amount of unknown HCl is then added to the 100-milliliter Erlenmeyer flask.
6. Add two drops of the indicator, phenolphthalein, to the acid in the flask.
7. Using the slider on the right hand side, add NaOH to the HCl in the Erlenmeyer flask (This action is known as titrate). Add the indicator until the color of the indicator turns a light shade of pink.
8. Record the volume.
9. If you went too far past the end point, please record the results of your trial. Include all sets of data in your lab report.
Part II: Titration with a pH Meter
1. Fill the 50-milliliter buret with a 0.25 molar NaOH solution.
2. Record volume.
3. Measure out between 20 milliliters and 40 milliliters of the unknown HCl solution. This amount must be different than the amount used in part I.
4. Record volume.
5. The amount of unknown HCl is then added to the 100-milliliter Erlenmeyer flask.
6. Insert the pH meter into the Erlenmeyer flask and record the initial pH of the acid. Remember to record the pH of the solution after every 5 milliliters of NaOH added.
7. Titrate the NaOH into the HCl until the buret is empty.

Data and Observations:

Part I: Titration with an Indicator Part 1 | Trial 1 | Trial 2 | Trial 3 | Volume of NaOH | 50 mL | 50 mL | 50 mL | Volume of HCl | 30 mL | 25 mL | 35 mL | Final amount of NaOH | 30 mL | 34 mL | 30 mL |

Part II: Titration with a pH Meter Part 2 | Trial 1 | Trial 2 | Trial 3 | Initial Volume of NaOH | 50 mL | 50 mL | 50 mL | Volume of HCl | 25 mL | 30 mL | 35 mL | pH when 0 mL of NaOH is added. | 0.70 pH | 0.70 pH | 0.70 pH | Remaining volume of NaOH | 7.00 mL | 7.00 mL | 7.00 mL | pH solution after every 5 mL’s of NaOH is added. 5/10/15/20/25 | 0.9/1.15/1.5/7.00/12.4 |