Experimental Determination of the

Percent of Acetic Acid In Vinegar

Wear goggles! Use extreme caution when using acids and bases! If you spill an acid on your skin or clothes, rinse the area well with plenty of water, followed by baking soda. If you spill a base on your skin or clothes, rinse the area well with plenty of water, followed by vinegar. Notify your teacher at once.

PROCEDURE:

1.  Fill a buret as directed with a 1.00 M NaOH solution. Use extreme caution. NaOH is caustic. Record the initial volume of the NaOH in the data table.

2.  Find the mass of a 250 mL Erlenmeyer flask and record this mass on the data table.

3.  Use a graduated cylinder to measure exactly 20.0 mL of vinegar. Add the vinegar to the flask. Record the mass of the flask and vinegar in the data table. Record the exact volume of the vinegar in the data table.

4.  Add three drops of the indicator phenolphthalein to the vinegar in the flask. Swirl the flask gently to thoroughly mix the contents of the flask.

5.  Titrate the 1.00 M NaOH into the flask containing the vinegar. Continue until a pale-pink endpoint of neutralization is reached. If you are careful, the addition of one final drop of NaOH should cause the color change.

6.  Find the meniscus on the buret. Record the volume of NaOH used during the titration.

DATA TABLE:

Mass of flask and vinegar ______

Mass of flask ______

Mass of vinegar ______

Volume of vinegar (in mL) ______

Volume of vinegar (in L) ______

Initial volume of NaOH (in mL) ______

Volume of NaOH used in titration (in mL) ______

Volume of NaOH used in titration (in L) ______

CALCULATIONS:

1.  Calculate the moles of NaOH used in the titration. Show calculation to receive full credit.

2.  Write the balance equation for the neutralization reaction. Include physical state symbols.

3.  Find the moles of acetic acid neutralized. Show all work.

4.  Find the molar mass of acetic acid. Show all work.

5.  Calculate the mass of acetic acid in vinegar. Show your calculations to receive full credit.

6.  Find the mass percent of acetic acid in vinegar. Show your calculations to receive full credit.

7.  What is the manufacturer’s claim of acidity in this vinegar(from the label)? Calculate your percent error.