Two different methods were used in determining the content of acetic acid. Industrial quality control chemists do this to maintain product quality. You and your partner should take turns performing these titrations. The concentration of acetic acid in vinegar was 0. The known percent of acetic acid in vinegar is 5%.
One major factor that affected the result of this experiment was to strength of the sodium and sodium hydroxide. Therefore, volume dispense from the burette should be estimated to the nearest 0. Part I ended with a chart of all the. Using a pH meter and a graph of pH plotted versus the volume of base added, the equivalence point can be accurately found by finding the point that is in the middle of the vertical part of the curve. Lab Investigation 2 - How Much Acetic Acid is in Vinegar? In this experiment, the equivalence point occurs when the moles of acid in the solution equals the moles of base added in the titration. Indicators are chosen so the endpoint is very close to the equivalence point. Although there were results there were some likely sources of error.
In the first part of the experiment, a visual indicator was used to find the acetic acid content. The purpose of this lab was to first determine the pH of different household items, and to then determine the concentration of acetic acid in vinegar. The phenolpthalein, a acid —base color indicator will let us know the vinegar have reach a point of neutralization once the vinegar turns pink. Repeat this process for two more trials. The endpoint has been reached when a faint pink color persists for at least 30 seconds.
Introduction: Vinegar is a dilute solution containing acetic acid. The equation is then solved for x, ignoring the x in the denominator. Phenolphthalein is nearly colorless in acidic solution but turns pink at a pH of about 8. Depending on the test performed, certain results acquired, clearly identified the macromolecules present in each food sample. Placing the card behind the buret and the black line just below the meniscus darkens the meniscus for easy reading. How would your results have differed if the tip of the burette was not filled with sodium hydroxide before the initial volume reading was recorded? Your starting volume does not have to be zero. The first method used was titrating with a visual indicator.
Chemical reactions in a calorimeter were used to determine the amount of heat produced by a reaction. The reactions that occurred in during the experiment were neutralization reactions, meaning that the moles of acid equaled the moles base at the end of the experiment. Human judgment also accounts for some of the error in this experiment as the person performing the experiment was required to read off many measurements from the pipette and burette. There is not a significant difference between methods. These uncertainties are then applied to calculations in order to keep up the amount of uncertainty associated with the amount of material used. Equivalence point can then be determined from a graph of data collected. The concentration was found to be 4.
Slip the clamp into the textbook by placing the test tube clamp into the middle of the book. Be careful not to scratch the inner surface if you find it necessary to use a buret brush to clean it. Therefore, for every one mole of calcium carbonate that reacts, 2 moles of acetic acid have reacted as well. When starch is presence, the iodine lodges. The color may then fade after sitting for several minutes due to carbon dioxide in the atmosphere. Most commercial vinegar is labeled as 5% acetic acid, but can have a mass percentage of between 4.
If either of these substances is left open in the atmosphere, they begin to lose their strength. The results should show that the content is close to 5% because the vinegar claimed to have this content of acetic acid. Record in the spaces provided. If the experiment were performed again, there would be only one change I would make. Once the equivalence point of the titration is known, the concentration of the sodium hydroxide can be determined.
Personally, I think the method of using a visual indicator is quicker than using a pH meter. Sodium hydroxide solution of 250 ml of approximately 0. For this first lab, you will need your titrations to agree to within 0. Fermentation creates vinegar when sugars are converted into alcohol and carbon-dioxide. With the aid of the results from the lab, the unknown solution will also be determined.
Daphny Maldonado Bio Lab 2107 Kiah Britton W 10-12:30 Is H20 Bad for You? Keep the pH meter immersed in water. There were four infants affected by this cluster. A titration is an analytical procedure in which a reaction is run under carefully controlled conditions. You do not need to flush the tip of the burette again. Calculate the mass of the acetic acid in grams using the previously given equation. These uncertainties can be reduced by using more accurate equipments, for example a more accurate mass balance.