Lab: Titration with an Indicator

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 astitrate). 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
Insert a complete data table, including appropriate significant figures and units, in the space below. Be sure to include all trials that were completed in Part I. Also include any observations that you made over the course of Part I.
I. A data table for recording your observations is below.
Part I: What was Measured | Measurement | Volume of HCl used | 20.0 mL | Initial volume of NaOH in buret | 50.0 mL | Final volume of NaOH in buret | 34.0 mL |
Observation: The color in the flask changed from no color to a light pink color.
Part II What was Measured | Measurement | Volume of HCl used | 30.0 mL | Initial volume of NaOH in buret | 50.0 mL | Final volume of NaOH in buret when end point was reached | 26.0 mL | Initial pH of HCl | 0.70 | pH after 5 mL NaOH added | 0.87 | pH after 10 mL (total) NaOH added | 1.06 | pH after 15 mL NaOH added | 1.30 | pH after 20 mL NaOH added | 1.70 | Volume at which pH=7.0 | 24.0 mL NaOH added to the flask (26.0 mL left in buret) | pH after 25 mL NaOH added | 11.65 | pH after 30 mL NaOH added | 12.40 | pH after 35 mL NaOH added | 12.63 | pH after 40 mL NaOH added | 12.76 | pH after 45 mL NaOH added | 12.85 | pH after 50 mL NaOH added | 12.91 |
Observation: The pH meter detected a pH of 7.0 when 24.0 milliliters of sodium was added to the flask.