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Title: Acid Base Titration

Purpose: To determine the concentration of an acid through the method of titration.

Introduction: Discuss the theory of titration

Procedure:

1. Obtain two burettes. Fill one to the top (but still within the marks) with a solution of 0.10 M NaOH. Fill the other to the top with a solution of HCl of unknown concentration. Make sure that you keep track of what is in each burette!

2. For all subsequent steps of the procedure, be sure that you record the volume of liquid in the burette both BEFORE and AFTER the titration.

3. Transfer approximately 10 mL of the acid into a clean Erlenmeyer flask. Add 50 mL of distilled water and 1-2 drops of phenolphthalein to the flask. Titrate the HCl with the NaOH solution. Note: if you overshoot the end point in these titrations, you will have to discard the sample and begin again. Do three full titrations (that you did not overshoot).

4. Rinse all equipment thoroughly with tap water.

Data:

Trial Number

Initial volume

of HCl (mL)

Final Volume

of HCl (mL)

Initial Volume

of NaOH (mL)

Final Volume

of NaOH (mL)

1

       

2

       

3

       

Analysis:

1. Determine the number of moles of NaOH required for each titration.

2. Determine the number of moles of HCl that must have been present in the Erlenmeyer flask at the beginning of the titration.

3. Determine the molarity of the HCl prior to adding distilled water to it.

Questions:

1. In you determination of the concentration of the HCl, does it matter how much distilled water you add to the Erlenmeyer flask. Explain thoroughly using evidence from your calculations.

2. Will your determination of the concentration of HCl be affected by the amount of HCl with which you started the titration? Explain.