What happens if too much phenolphthalein is added to a solution in a titration?
Answer:
NO, it won't have a significant effect on the concentration of your substance if you have added too much phenolphthalein in the solution. Phenolphthalein is just an indicator. In neutralization reaction, the acid in your solution will be neutralized first. After all of the acid is neutralized, it is just then that your phenolphthalein will start reacting with the base giving a light pink color.
This is also the reason why end point using phenolphthalein indicator needs to be light pink. If the pink color becomes intense, it means that more of the phenolphthalein molecules has reacted with the base, which means too much base has been added (than the correct amount for neutralizing your acid) - giving an erroneous result in the computation for the acid concentration.
It's hard to add too much.
Pheolpthalein is a weakly acidic compound. Therefore, if you add it to an acid, you are putting "more" acid in there which means that you would need more base to cause neutralization so your volume of base would be larger (and since volume of base is in the denominator in concentration of acid calculations, the acid concentration would be lower than it really is.
But you have to add A LOT. Not just like 10 drops, like mLs worth
Burette reading will not be accurate. The transition range may shift slightly depending on the concentration of the indicator in solution and on the temperature at which it is used.
Phenolphtalein is simply an indicator. It changes color at a certain pH. Adding more phenolthalein will have virtually no effect on your result. The only way it would have an effect is if you were determining a percent composition that was extremely small.
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: