- What effect would be on the normality of unknown acid? Explain why. (standarized
NaOH in the burette)
a) if a wet burette is used for NaOH (that has a known normality)
b) if a wet conical flask is used for the titration against the acid
c) if an air bubble is out from the burette
i know for A that water will dilute the base causing an error in calculations of the unknown acid concentration .. i cant figure the effect on normality though ?
For a.
eqn 1. mols NaOH = M NaOH x L NaOH
eqn 2. mols acid = mols NaOH
eqn 3. M acid = mols acid/L acid
You're right, the NaOH is diluted which means you will add MORE NaOH when you titrate the acid. Look at eqn 1, If you add more volume you THINK you have more mols NaOH, that leads to more mols acid from eqn 2 and that increases the M of the acid from eqn 3.
Didn't Devron answer this for you a day or so ago?
For b. If a wet flask is used for the titration the M of the acid is unchanged. It's true you dilute the acid when you add it but it's also true yu dilute the base when you titrate. The water doesn't affect mols acid used or mols NaOH used.
c. If an air bubble in the buret is released during the titration it means the buret reading is too high because you've measured the volume of the base used as well as the volume of the air bubble. Now follow that from eqn 1, 2, 3.
The normality of a solution is a measure of the concentration of a solute in a solution. It indicates the number of equivalents of the solute present per liter of solution. In order to answer your question, we need to understand the effect of each situation on the normality of the unknown acid.
a) If a wet burette is used for NaOH (that has a known normality):
When a wet burette is used, some water may be present in the burette along with the NaOH solution. This extra water will dilute the NaOH solution and reduce its effective concentration. As a result, when titrating against the unknown acid, the actual normality of NaOH will be lower than what it should be. This will lead to an underestimation of the normality of the unknown acid.
b) If a wet conical flask is used for titration against the acid:
Similarly, if a wet conical flask is used, some water may be present in the flask before the acid is added. This extra water will dilute the acid and reduce its effective concentration. As a result, when titrating with NaOH, the actual normality of the acid will be lower than what it should be. This will again lead to an underestimation of the normality of the unknown acid.
c) If an air bubble is present in the burette:
When titrating, it is important to ensure that there are no air bubbles trapped in the burette. Air bubbles can occupy the space that should be filled with NaOH solution, leading to an erroneously reduced volume of solution being used in the titration. This will result in an overestimation of the normality of NaOH and an underestimation of the normality of the unknown acid.
In summary, using a wet burette or a wet conical flask can lead to an underestimation of the normality of the unknown acid, while an air bubble in the burette can lead to an overestimation of the normality of NaOH and, consequently, an underestimation of the unknown acid's normality.