14. Calculate the total volume of NaOH that was required to reach the endpoint and record the data in Data Table 1. 15. Dispose of the titrated vinegar sample in the sink. 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: To gain more control of single drops from the syringe, move the plunger by holding it where it enters the syringe instead of pressing the end of the plunger.
8 Example: A sample of 10.0 mL of HCl unknown concentration is titrated to the endpoint with 6.2 mL of a 1.0 M NaOH sample. Calculate the concentration of hydrochloric acid. 1.Write out balanced chemical equation HCl + NaOH H2O + NaCl 2.Determine the moles of sodium hydroxide used to reach the endpoint. 3.Determine the moles of hydrochloric acid in the sample. 4.Calculate the molarity of hydrochloric acid
©2015, Carolina Biological Supply Company 9 Data Table 1: Titration of Vinegar with Sodium Hydroxide Vinegar Sample 1 Vinegar Sample 2 Vinegar Sample 3 Mass of Vinegar Volume of Vinegar Density = 1.005 g/mL Initial NaOH volume in syringe Final NaOH volume in syringe Volume of NaOH Delivered Moles of NaOH Delivered Moles of Acetic Acid in Sample Mass of Acetic Acid in Sample Calculated Molarity of Acetic Acid in the sampled vinegar Calculated Percent Mass of Acetic Acid in sampled vinegar Average Calculated Percent Mass of Acetic Acid in Sampled Vinegar 5.03 g 5.05 g 4.98 g 5.00 ml 4.99 ml 4.99 ml 10.00 ml 10.00 ml 10.00 ml 5.2 mL 4.5 ml 4.5 ml 4.8 ml 4.5 ml 4.5 ml 0.0058 0.0056 0.0056 0.0058 0.0056 0.0056 .34521 g .33032g .33032 g .575 .55 .55 11.45 11 11 11.15
©2015, Carolina Biological Supply Company 10 Activity 2: Titration of an Unknown Vinegar Sample with Sodium Hydroxide Activity 2 is an inquiry-based activity to demonstrate the learned technique of determining the acetic acid concentration in vinegar to a vinegar sample from your home. Each type of vinegar has a slightly different concentration of acetic acid. This activity requires the selection of a vinegar product from your home, a friend’s home, or a local restaurant. Only about a teaspoon of vinegar is needed. Attempt to find a different type of vinegar such as cider, malt, or balsamic vinegar. The vinegar included in this kit is white vinegar. Different brands of vinegar may also contain different amounts of acetic acid. Use the same procedure and data table to determine the acetic acid content in your vinegar sample. Disposal and Cleanup 1. Dispose of titrated samples in the sink. 2. Clean and dry the flask and return it to the equipment kit. 3. Return unused chemicals to the chemical kit. 4. Sanitize work space.
©2015, Carolina Biological Supply Company 11 Data Table 2: Titration of Second Vinegar Sample with Sodium Hydroxide Name of Vinegar Sample Vinegar Sample 1 Vinegar Sample 2 Vinegar Sample 3 Mass of Vinegar Volume of Vinegar Density = 1.005 g/mL Initial NaOH volume in syringe Final NaOH volume in syringe
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