Table of Contents
Why is phenolphthalein used in weak acid strong base titration?
Explanation: A weak-acid strong base titration involves a end-point/neutralization point at a pH higher than conventional 7 and usually around 9-10. Phenolphthalein has a color change around this range as well and thus we use this.
Why is phenolphthalein used in titration instead of 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 is phenolphthalein used as an indicator in saponification value of fats?
Phenolphthalein 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 phenolphthalein is a weak acid?
Because it indicates the pH of the solution, it is colourless below 8.5 pH and is able to attain a pink to deep red colour above 9.0 pH. Phenolphthalein is a weak acid and it dissociates in water to give pink anions. Hence, we can say that phenolphthalein is a weak acid.
When phenolphthalein is used as the indicator in a titration of an HCl?
When phenolphthalein is used as the indicator in a titration of an HCl solution with a solution of NaOH, the indicator undergoes a colour change from colourless to poink at the end point of the tiration.
Why is the choice of indicator more crucial for a weak acid strong base titration than for a strong acid strong base titration?
Because the pH change near the equivalence point becomes smaller as Ka decreases, the choice of indicator for a weak acid-strong base titration is more critical than it is for a strong acid-strong base titration.
Why is phenolphthalein a better indicator for this experiment than methyl orange?
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. Hence methyl orange is a better indicator in this case.
Why did you use phenolphthalein and methyl orange indicator specifically?
Answer : The role of phenolphthalein and methyl orange indicator in titration is to determine the equivalence point when the color change. Explanation : Indicator : It is a substance that changes the color in the response to a chemical change.
Which indicator is used in saponification value of oil?
phenolphthalein indicator
Saponification value is a measure of the content of ester linkages. It is determined by back titration of potassium oxide in the presence of phenolphthalein indicator with 0.5 N sulfuric or hydrochloric acid.
What is the importance of saponification value?
Saponification is important to the industrial user for it helps to know the amount of free fatty acid that is present in a food material. The quantity of free fatty acid can be distinguished by determining the quantity of alkali that must be added to the fat or oil to make it neutral.
What is the pH of phenolphthalein?
Phenolphthalein is fuchsia in pH’s roughly between 8.2 and 12, and is colorless below pH 8.2. When the number of moles of added base is equal to the number of moles of added acid (or vice versa; example valid for strong monoprotic acids/bases assuming 100\% dissolution), the pH is equal to 7. You might say, if the pH needed is 7,…
Why Phenolphthalein is used as an indicator in acid base titration?
Explain why phenolphthalein is used as an indicator in acid-base titration. Phenolphthalein is a weak organic acid. Its undissociated molecule (HPh) is colourless while its ion (P h−) is pink in colour. pH range of Phenolphthalein is 8−9.8.
What is the PIN value of phenolphthalein used as an indicator?
The indicator works best for pH=pIn + (+/- ) 1. The pH value at equivalence point for weak acid – strong base will be towards basic side. The pIn of phenolphthalein lies in this basic range making it suitable for said purpose. Any indicator with such pIn value can be used. How can I save money on my prescriptions?