Why do we use phenolphthalein as an indicator in NaOH and HCl titration?
Table of Contents
- 1 Why do we use phenolphthalein as an indicator in NaOH and HCl titration?
- 2 Why phenolphthalein and methyl orange are used as indicators?
- 3 What is the indicator for HCl and NaOH?
- 4 What happens when methyl orange is added to NaOH?
- 5 What is the colour of methyl orange in Naoh?
- 6 When to use methyl orange or phenolphthalein as indicator in titration?
- 7 What is the equivalence point of NaOH and HCl?
Why do we use phenolphthalein as an indicator in NaOH and HCl 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. Neutralization is the basis of titration.
Why phenolphthalein and methyl orange are used as indicators?
Methyl orange and phenolphthalein use as indicator , In Acidic solution Methyl orange gives red colour but in basic solution it gives yellow colour . In Acidic solution phenolphthalein is colourless but in basic it gives pink colour . They both are used as a pH indicator.
Why phenolphthalein is used as indicator in both titrations and not methyl orange?
If you use phenolphthalein, you would titrate until it just becomes colourless (at pH 8.3) because that is as close as you can get to the equivalence point. On the other hand, using methyl orange, you would titrate until there is the very first trace of orange in the solution….
| indicator | pKind |
|---|---|
| phenolphthalein | 9.3 |
Why methyl orange is used as an indicator in titration?
Methyl orange is a pH indicator frequently used in titration because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the pKa of a mid strength acid, it is usually used in titration for acids.
What is the indicator for HCl and NaOH?
Imagine we are adding NaOH(aq) to HCl(aq) in a conical flask. Initially there is a large excess of acid, the solution is acidic, and the phenolphthalein indicator is colourless. BUT phenolphthalein changes colour between pH 8.3 and 10.0, so, at the equivalence point the phenolphthalein remains colourless.
What happens when methyl orange is added to NaOH?
When methy orange is added to a solution of NaOH then it will impart a yellow colour. Methy orange generally changes from yellow to red in acidic medium.
Why is Methyl Red used and not methyl orange is used as the indicator?
Soc., 1910, 97, 2477) concluded that g L as an indicator methyl red is greatly superior to methyl orange, as the colour curves show. It is quite true that the end-point with methyl red is sharper than with methyl orange when these indicators are simply tested in water with acid or alkali.
What happens when methyl orange solution is mixed with HCl?
When methyl orange is added to dilute hydrochloric acid, the color of the solution gets converted into red. When methyl orange is used as an indicator with acid, the color of the solution turns red. When methyl orange is used as an indicator with base, the color of the solution turns yellow.
What is the colour of methyl orange in Naoh?
When methyl orange indicator is added to sodium hydroxide (a base), It changes its colour from orange to yellow.
When to use methyl orange or phenolphthalein as indicator in titration?
When you titrate a strong base ( such as NaOH) with a strong acid (such as HCl , it is acceptable to use either methyl orange or phenolphthalein as indicator. These two indicators have colour changes at different pH , – MO changes from red → yellow orange at pH 3.1 – 4.4 and phenolphthalein changes from colourless →purple at pH 8.2 – 9.8 .
Which indicator is used in titration of NaOH and HCl?
In the given question, both NaOH and HCl are strong base and strong acid respectively and so either PHENOLPHTHALEIN or Methyl orange can be used as indicators. In the Titration of a strong base versus a weak acid such as acetic acid, PHENOLPHTHALEIN is used as the indicator. NaOH is a strong base.
Why does phenylphthalene change colour in titration with NaOH and HCl?
Because NaOH is a strong base and HCl is a strong acid, the equivalence point will occur at pH 7. The best indicator should therefore change colour at around pH 7. Phenylphthalene, however, changes colour somewhere between pH 8.3 – 10, which incidentally makes it an ideal indicator for a titration of a strong base and weak acid.
What is the equivalence point of NaOH and HCl?
Because NaOH is a strong base and HCl is a strong acid, the equivalence point will occur at pH 7. The best indicator should therefore change colour at around pH 7.