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4.Record the exact mass of vinegar in Data Table 1. 5.Transfer the vinegar into the clean 25-mL Erlenmeyer flask. 6.Add 2 drops of phenolphthalein to the vinegar. 7.Transfer approximately 10 mL of 1 M sodium hydroxide (NaOH) to the small cup. This solution will be used to fill the syringe. 8.Fill the syringe with 1 M NaOH solution. Try to minimize the amount of air in the syringe. 9.Record the initial volume of NaOH solution in the syringe to the nearest 0.1 mL in your Data Table 1 for Vinegar Sample 1. Read the volume of the syringe at the edge of the plunger. 10.Place the flask containing the 5.0 mL vinegar on the white sheet of paper. The white background will make the color change more noticeable. 11.Add NaOH from the syringe in 0.5-mL increments, swirling the flask between each additionuntil a color changes persists for a few seconds after the addition of the NaOH. 12.Add NaOH dropwise from the syringe, with constant swirling, until a single drop of NaOH causes a color change that persists for a few seconds after addition. This indicates that theendpoint has been reached. 13.Once the endpoint has been reached, record the final volume of NaOH in the syringe in Data Table 1 for Vinegar Sample 1. 14.Calculate the total volume of NaOH that was required to reach the endpoint and record thedata in Data Table 1. 15.Dispose of the titrated vinegar sample in the sink.
2 16.Rinse the 25-mL flask three times with water. 17.Repeat steps 1–16 for Vinegar columns 2 and 3 on Data Table1. 18.Calculate the concentration of acetic acid in your vinegar sample based on your experimental data. See the following example: