Table of Contents
- 1 Is phenolphthalein the best indicator for this experiment?
- 2 Why is bromothymol blue a good indicator for titration?
- 3 Why is phenolphthalein a better indicator than methyl?
- 4 Is phenolphthalein a universal indicator?
- 5 Why phenolphthalein is not a suitable indicator in the titration of a strong acid vs weak base?
- 6 Why is phenolphthalein bad?
- 7 What is the pKa of phenophthalein and bromothymol blue?
- 8 Why is Bromophenol blue used instead of phenolphthalein in antacid titration?
Is phenolphthalein the best indicator for this experiment?
– Other indicators like methyl orange change its colour at around a \[pH\]of 4. So, there is a considerable difference between the \[pH\]of the colour change of the indicator and the equivalence point for the titration of the weak acid and strong base. – So, phenolphthalein is the best indicator in this case.
Why is bromothymol blue a good indicator for titration?
Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). It is a good indicator of dissolved carbon dioxide (CO2) and other weakly acidic solutions. As the level of carbon dioxide or acid increases, the solution will gradually take on a yellow tint.
Why is phenolphthalein not a good indicator?
Hence the main reason is that phenolphthalein is a weaker acid than the acid that is to be titrated. NaOH is a strong base. HCl is a strong acid. So generally either Phenolphthalein or Methyl orange indicator can be used.
Which indicator would be the best to use for a 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.
Why is phenolphthalein a better indicator than methyl?
Methyl orange changes color at a pH of 3.4 whilst phenolphthalein does so at a pH of 9.3. Therefore, if you were titrating a strong acid with a weak base, then you would use methyl orange; and if you were titrating a weak acid with a strong base, phenolphthalein would be more appropriate than methyl orange.
Is phenolphthalein a universal indicator?
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions….Universal indicator.
| Indicator | Phenolphthalein |
|---|---|
| Low pH colour | Colourless |
| Transition pH range | 8.3 – 10.0 |
| High pH colour | Fuchsia |
Which indicator is best for weak acid strong base titration?
A suitable indicator for the titration of the weak acid CH3COOH(aq) and the strong base NaOH(aq) would be either thymol blue (pH range 8.0 – 9.6) or phenolphthalein (pH range 8.3 – 10.0).
Is Bromothymol Blue accurate?
How accurate is Bromothymol blue? Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). It is a good indicator of dissolved carbon dioxide (CO2) and other weakly acidic solutions.
Why phenolphthalein is not a suitable indicator in the titration of a strong acid vs weak base?
Answer: Why is phenolphthalein not a suitable indicator for titrating weak base against strong acid? – Quora. Because the equivalence point of a weak base-strong acid system is likely going to be outside of the color indicator range of phenolphthalein.
Why is phenolphthalein bad?
Ingestion: Harmful if swallowed. May cause irritation of the digestive tract. Ingestion may cause fever, blood pressure increase and other unspecified vascular effects. Inhalation: May cause respiratory tract irritation.
How does phenolphthalein indicator work in titration?
Phenolphthalein is often used as an indicator in acid–base titrations. When a base is added to a solution containing phenolphthalein, the equilibrium between the nonionized and the deprotonated states shifts in favor of the deprotonated state as H+ ions are removed from solution.
Why is phenolphthalein a good indicator for weak acid strong base titration?
Stages of a Strong Acid-Strong Base Titration 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.
What is the pKa of phenophthalein and bromothymol blue?
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. BTB is a good choice for any titration with an equivalence point near neutral.
Why is Bromophenol blue used instead of phenolphthalein in antacid titration?
For example, bromophenol blue shows a change in color in range between pH 3.0 to pH 4.6 and phenolphthalein shows a color change in range between pH 8.3 to pH 10. Hence, bromophenol blue is used as an indicator rather than phenolphthalein in antacid titration.
When to use phenolphthalein as an indicator?
If the solution is brilliant re in alkalies and decolorized by acids it’s the time to used phenolphthalein in analysis as an indicator.
What is the color change of phenolphthalien at pH 7?
The color change of phenolphthalien is about pH9–which is a partial drop of volume of a strong base (1 drop of 0.1M OH- titrant is more than enough to turn the color). Bromothymol blue has a very sharp color change around pH7, that may be so quick as to cause an undertitration. 8 clever moves when you have $1,000 in the bank.