Can methyl orange be used to replace phenolphthalein as an indicator?
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Can methyl orange be used to replace phenolphthalein as an indicator?
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 do we use phenolphthalein as an indicator in standardization of NaOH?
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 do we use phenolphthalein and methyl orange?
Acid base titration indicators Typically, we use methyl orange and phenolphthalein to determine end points of acid-base titration. The selection of a particular indicator for the titration is decided on the basis of plot known as pH curve, which is typical of a particular reaction.
Why is methyl orange better than phenolphthalein?
If the strong acid is in burette, then methyl orange is a better choice as the colour change from yellow to orange is very sharp. In this case, the colour change observed if phenolphthalein is used is from pink to very pale pink. The difference between pale pink and colourless is almost indistinguishable.
Why do we use phenolphthalein and not another indicator for this experiment?
Phenolphthalein is used for titrations as it is a single indicator and so only has two different colours (pink for alkaline solutions and colourless for acidic solutions).
Why is methyl orange used in carbonate titration and not phenolphthalein?
When titrating carbonates, which are weak acids, we typically use strong acids. When we use something like phenolphthalein as the end-point indicator, the color change corresponds to the first reaction. Methyl orange is a pH indicator frequently used in titrations because of its clear and distinct colour change.
Why methyl orange is not suitable as an indicator?
– The pH at the end point will be greater than 7, which is slightly alkaline. As the pH at the end point is not at the range of methyl orange (3–5), methyl orange will not be able to act as an indicator in this titration as we will not be able to see a colour change when the reaction completes.