Planning and Designing Chemistry Lab- Determining if three different brands of vinegar contain the same concentration of ethanoic acid

Planning and Designing Chemistry Lab- Determining if three different brands of vinegar contain the same concentration of ethanoic acid

Problem:

Do Different brands of vinegar contain the same concentration of ethanoic acid

Hypothesis:

Different brands of vinegar contain varying concentration of ethanoic acid due to the presence of different ingredients in each.

Aim:

To determine whether three (3) different brands of vinegar contain the same concentration of ethanoic acid using titration.

Apparatus / Method:

three different brands of vinegar containing ethanoic acid, 0.1moldm3 Sodium carbonate (Na2CO3), phenolphthalein indicator, pipette, burette, retort stand, conical flask.

Method:

  1. Rinse burette several times with water, then condition it using the sodium carbonate.
  2. Set up titration apparatus and fill the burette with the sodium carbonate solution. Ensure no air bubbles are present in the burette.
  3. Record the volume of sodium carbonate in the burette to two decimal places. This is the initial volume used in the titration.
  4. Pipette 25ml of one brand of vinegar in a clean dry conical flask.
  5. Add 3 drops of phenolphthalein to the flask.
  6. Begin the titration; ensure that the flask is continuously swirled until the end point is reach. (Color change from colorless to pink).
  7. Record the final burette reading.
  8. Repeat the process until two accurate volumes (no more than 0.1 from each other) is obtained.
  9. Repeat Steps 1-8 for the other two brands of vinegar and tabulate results.

Variables:

  • Controlled: the concentration of carbonate used and the amount of indicator used.
  • Manipulated: the brands of vinegar
  • Responding the amount of carbonate used to neutralize the different brand of vinegar

Expected Results:

Chemistry diagram 9

Interpretation of Results:

 

The vinegar solution that contains the least amount of ingredients will take less volume for a complete neutralization of occur as there is a low concentration of ethanoic acid present.

 

The vinegar solution that has more constituents in the ethanoic acid will thus have a higher concentration and will required more carbonate to neutralize the acid. If the data shows this then the hypothesis is accurate.

 

Limitations:

  • Incorrect reading of the volume in the burette
  • Passing the end point thus using too much of the carbonate, thus altering the results.

 

Assumption:

All brands of vinegar contain a different amount of ethanoic acid due to the varying number of other ingredients present in each.