Such that the concentration of a phenolphthalein indication turns bright pink? Does this mean that the acid has been completely neutralized and that the concentration is zero? Or is there still some acid left in the mixture?
2007-10-02 06:43:28 · 3 answers · asked by blueanswers 2 in Science & Mathematics ➔ Chemistry
So does this mean that the acid is neutralized, yet there are still H+ ions in the mixture?
2007-10-02 07:10:40 · update #1
HA + BOH --> H2O + BA
When the phenolphthalein turns bright pink, the acid has been totally neutralized and the base is in excess.
In water solution you always have this equilibrium-
2H2O <--> H3O+ + OH-
This means you always have some H3O+ ions even in a strongly basic solution.
2007-10-02 06:55:37 · answer #1 · answered by skipper 7 · 1⤊ 0⤋
The concentration of the acid is zero.
Phenolphthalein is colorless if a solution is acid. If it becomes basic, the indicator becomes a bright pink. This means all the acid will have been consumed by the base. A completely neutral solution will have a pH of 7. This will be the point at which the acid and base exactly balance one another. Phenolphthalein is chosen as an indicator because it is very easy to see. It does not indicate the exact balance point, but it is close enough to be useful for titrating acids and bases.
2007-10-02 14:03:05 · answer #2 · answered by Roger S 7 · 1⤊ 0⤋
Phenolphthalein turns colorless to pink over a pH of 8-10. This means that [H+] = 10^-10 or so. So if you count that, then there is still "some acid" in the mixture.
2007-10-02 13:49:12 · answer #3 · answered by steve_geo1 7 · 2⤊ 0⤋