Table of Contents
- 1 Why do we use phenolphthalein as an indicator in titration of strong acid and strong base?
- 2 Which indicator is useful for the titration of weak acid and strong base?
- 3 What indicator is best for titration?
- 4 Why phenolphthalein is used in titration experiment?
- 5 Why do we use bromothymol blue and phenol red as indicators?
Why do we use phenolphthalein as an indicator in titration of strong acid and strong base?
A strong acid- strong base titration is performed using a phenolphthalein indicator. Phenolphtalein is chosen because it changes color in a pH range between 8.3 – 10. It will appear pink in basic solutions and clear in acidic solutions.
Why is phenolphthalein not a suitable indicator for titrating weak base against strong acid?
In the same way in the Titration of weak base versus strong acid there is a sudden change in the pH of 3.5 to 8.0,near the neutralisation point. So Phenolphthalein can’t be used since its pH range is 8.3 to 10.0.
Is Bromothymol blue or phenolphthalein a better indicator?
Bromothymol blue is the best of the three indicators for this titration. For the weak acid, the methyl orange color change will occur long before the equivalence point, the bromothymol blue change is slightly premature, and phenolphthalein color change occurs close to the correct place (around pH 8.9).
Which indicator is useful for the titration of weak acid and strong base?
Phenolphthalein
Choice of Indicators
| Types of titration | Indicators |
|---|---|
| Strong acid-strong base | Phenolphthalein is usually preferred because of its more easily seen colour change. |
| Weak acid-strong base | Phenolphthalein is used and change sharply at the equivalence point and would be a good choice. |
What is the importance of phenolphthalein in titration process?
Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.
Why is phenolphthalein a good indicator?
Phenolphthalein changes colour at a pH above 7. So it is quite good as an indicator for titrations of strong acids with strong bases. It is also suitable for titrations of weak acids and strong bases, which have an equivalence point at a pH above 7.
What indicator is best for titration?
phenolphthalein
The indicator phenolphthalein, whose range spans from pH 8 to 10, therefore makes a good choice for this type of titration. If you don’t know the pH change around the equivalence point of your titration, consult a general chemistry textbook.
Is Ethanoic acid a strong acid?
Ethanoic acid is a weak acid which means it does not fully dissociate into ions in water. Hydrochloric acid is a strong acid and dissociates fully.
Why do we use phenolphthalein as an indicator in titration?
Phenolphthalein is used as an indicator in acid-base titration as it indicates the change in pH by changing its colour [actually, going from colourless (in acidic solution) to pink colour(in basic solution)].
Why phenolphthalein is used in titration experiment?
Why is phenolphthalein used in the experiment? Phenolphthalein is used as indicator for titrations for titrations. Phenolphthalein is used because it changes colour close to pH 7, the pH of the equivalence point of a strong acid with a strong base. The phenolphthalein has an easy colour change, from colourless to pink.
Which is better phenophthalein or bromothymol blue titration?
You’ll find that the pKa of phenophthalein (9.5) is greater than that of bromothymol blue (7.3). A weak acid being titrated by a strong base will have an equivalence point on the alkaline side of neutral and so should better be matched by Phph than by BTB.
What is the role of phenolphthalein in titration of acid?
Phenolphthalein changes colour at a pH above 7. So it is quite good as an indicator for titrations of strong acids with strong bases. It is also suitable for titrations of weak acids and strong bases, which have an equivalence point at a pH above 7. It is not a good choice for a titration between a strong acid and a weak base, as the equiva
Why do we use bromothymol blue and phenol red as indicators?
In the discussion above, we decided that we could use bromothymol blue or phenol red as indicators for the titration of NaOH (aq) (a strong base) with HCl (aq) (a strong acid) because these indicators change colour over a range of pH values that includes the pH of NaCl (aq) (the salt produced in the neutralisation reaction):
What is the equivalence point of phenolphthalein at pH 10?
Phenolphthalein has a color change point ranging from pH 8.2–10, which is suitable for acid-base combinations where the equivalence point will be in that range, but the system you describe is likely to have an equivalence point occur at a much lower pH, since the conjugate acid of a weak base is a relatively strong acid.