Discuss briefly a comparison of the two vinegars or for an analysis of a single vineg the relative standard deviation. Data Analysis C and D ar, calculate the standard deviation an Laboratory Questions Circle the questions that have been assigned. 1. Part A.2. A 20-mL volume of previously boiled, deionized water is added to the Erlenmeyer flask to prepare the sample for titration. Explain why this volume is not
critical to the analysis. (2, Part A.2. Previously boiled, deionized water is unavailable. In a hurry to pursue the analysis, deionized water (not is added. How does this attempt to expedite the analysis affect the reported percent acetic acid in vinegar: too boiled) high, too low, or unaffected? Explain.
The Correct Answer and Explanation is :
Part A.2: Explanation of the Role of Boiled, Deionized Water in the Titration Process
In a titration process, precise measurements of a reagent’s concentration are crucial for accurate results. The addition of a 20-mL volume of previously boiled, deionized water is typically done to ensure that the solution is at a desired concentration for titration. This volume of water is not critical to the analysis in terms of its exact value because the primary goal is to dilute or adjust the volume of the vinegar sample to prepare it for titration, where the acetic acid concentration will be determined.
Boiling the deionized water before use serves to remove dissolved gases like carbon dioxide, which could potentially affect the titration process by altering the acidity of the solution. Deionized water is used because it does not contain any ions that could interfere with the titration.
Effect of Using Non-Boiled, Deionized Water on Percent Acetic Acid
If non-boiled, deionized water is used instead of the previously boiled variety, it may introduce dissolved carbon dioxide into the solution. This dissolved CO₂ can react with the water to form carbonic acid, which could slightly lower the pH of the solution. Since the titration is based on the neutralization of acetic acid with a base (such as NaOH), any slight decrease in pH could lead to an overestimation of the endpoint. This would result in the titrant being used in excess, potentially leading to an inaccurate calculation of the acetic acid concentration.
As a result, the reported percent acetic acid in the vinegar would likely be too high. The excess titrant used due to the lowered pH caused by the dissolved CO₂ would lead to an erroneous reading, increasing the calculated acetic acid concentration.
In summary, the use of non-boiled, deionized water could affect the titration by causing a slight increase in acidity due to dissolved CO₂, ultimately leading to an overestimation of the acetic acid content in the vinegar.