Lab Questions l. Explain what happens to the moles of H+] in the flask when you
ID: 1042057 • Letter: L
Question
Lab Questions l. Explain what happens to the moles of H+] in the flask when you add boiled, deionized water to rinse the wall of the flask during the titration. Explain what happens to the moles of OH needed from the buret to neutralize the acid after adding the water. What is the overall effect on the calculated acetic acid % of your sample? 2. Suppose that you do not add the water to rinse the wall of the flask, and several drops of base solution remain there. Explain what happens to the volume of base solution that you need to reach the endpoint. What is the overall effect on the calculated acetic acid % of your sample? 3. Deionized water absorbs CO2 when it is exposed to the air, and is boiled prior to this experiment to remove the CO2 CO, is an acid, and is equivalent to H,C03, so it creates H Suppose your deionized water is not boiled. Explain what happens to the moles of OH needed from the buret to neutralize the acid as a result. What is the overall effect on the calculated acetic acid % of your sample 4. Suppose your solution has a very faint pink color. The intensity of the pink color at the endpoint is a function of the amount of what substance that you added to your solution? Explain whether or not you need to add more NaOH solution to make the color darker. What is the overall effect on the calculated acetic acid % of your sample if you do add more NaOH? s. Suppose that you do not add the NaOH slowly and dropwise near the endpoint. Explain why this causes you overshoot the endpoint. Explain whether or not you can tell if you have passed the endpoint from the color of the indicator What is the overall effect on the calculated acetic acid % of your sample?Explanation / Answer
1. You already washed out all H+ ion with deionided water. So it is good & nothing any effect on Acetc acid titration.
So during titration overall effect is neglisible and result (% Acetic acid) having good accuracy.
Nothing any effect just acd base titration occure.
2. Here, in this case you dont wash base with water so it will effect on your titration Experiment and end effect to end point. Oveall in calcuation % Acetic acid is decreased. (base remain on flask react with acid and decrese required base amount so affect)
CH3COOH + NaOH ? CH3COONa + H2O
3. Here, because of H+ ion from H2CO3 uptake of more OH- ion along with uptake H+ by CH3COOH and automatically end point in increases and % Acetic acid increses.
4. If your end point is faint pink colour and you add excess of NaOH. This excess of NaOH do not take part in acid base raection only responsible for color changes to pink because of phenolphthalein is alkaline pH indicator. Due to more addition of NaOH affect the end point and not efftect the % Acetic acid (here, in this case you consider faint pink color as your end point). Therefore, you dont need to add more NaOH.
5. Here, if you do not add NaOH slowly at the end ponit, so you unable to get exact colr change from colorless to pink. You can get directly dark pink because of excess of unreacted NaOH increses alakline pH rapidly. Therefor you cant tell exact end point and It will automatically affect to your end point. Also efftect the % Acetic acid calculation.
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