If you forget to add phenolphthalein solution to a vinegar solution(after adding NaOH solution), how might you salvage the titration?
There are several ways but the main concept is to add enough acid to the titration flask to bring the pH back to the acid side. How to do that?
1. Add a primary standard acid such as potassium hydrogen phthalate then retitrate with the NaOH.
2. Add a measured amount (from a buret or a pipet) of a known molarity of HCl, then retitrate to the equivalence point with the NaOH.
If you forget to add phenolphthalein solution to a vinegar solution during a titration, there are a few ways you can salvage the titration process:
1. Restart the titration: The most straightforward solution would be to start the titration process from the beginning. This involves disposing of the solution and starting with a fresh sample of vinegar.
2. Use an indicator alternative: Phenolphthalein is commonly used as an indicator in acid-base titrations, but there are alternative indicators that can be used. One such alternative is bromothymol blue, which changes color around a pH of 6.0-7.6. You can add a few drops of bromothymol blue before continuing with the titration and monitor the color change in the solution as you add the NaOH solution.
3. Calculate the approximate volume: In some cases, you may be able to estimate the volume of NaOH solution that has reacted with the vinegar by measuring the volume of NaOH solution added and the initial concentration of the NaOH solution. By using stoichiometry and the reaction equation between NaOH and acetic acid, you can calculate the approximate volume of NaOH required to neutralize the vinegar.
However, it's important to note that the most accurate and reliable method would be to restart the titration or use the appropriate indicator.