Finding indicator for acid-base titration

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  • Thread starter haha0p1
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    Titration
In summary, at the endpoint of the titration, phenolphthalien will show a color change in an ammonia solution. This change will correspond to the pH of the solution.
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Homework Statement
Suggest a suitable indicator to find the end-points of the reaction below:
0.0500 mol/dm³ nitric acid and 0.0500 mol/dm³ aqueous ammonia.
Relevant Equations
Acid + Base = Salt + Water
This question is asking about finding the indicator. I think phenolphthalein will be used as there is a reaction between strong acid and strong base. Is this approach to the question correct? Or am I missing any important concept? Kindly tell
 
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  • #2
Ammonia solution is not a strong base...
What is the pH of ammonia, nitric acid and ammonium nitrate (the end product)
Check the pH that phenolphthalien changes colour at.
What colour will it show in the ammonia solution?
What colour will it show at the end point of the titration?
 
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  • #3
DrJohn said:
Ammonia solution is not a strong base...
What is the pH of ammonia, nitric acid and ammonium nitrate (the end product)
Check the pH that phenolphthalien changes colour at.
What colour will it show in the ammonia solution?
What colour will it show at the end point of the titration?
Ammonia is a weak base and nitric acid is a strong acid. Will methyl red be used?
 
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  • #4
haha0p1 said:
Ammonia is a weak base and nitric acid is a strong acid. Will methyl red be used?
That would depend on the pH around the equivalence point.
 
  • #5
Mayhem said:
That would depend on the pH around the equivalence point.
This is a two mark question. Can you tell how we will approach questions like this one.
 
  • #6
haha0p1 said:
This is a two mark question. Can you tell how we will approach questions like this one.
So this is a homework question. How do you like this idea: Try to perform a titration of a strong acid with ammonia solution. Monitor the entire titration with a pH meter. Find the inflection point pH. Making a graph might be needed. Now find a table of pH indicators and choose an indicator which has a color transition as near to the pH inflection point found, as you can find.
 
  • #7
haha0p1 said:
Homework Statement:: Suggest a suitable indicator to find the end-points of the reaction below:
0.0500 mol/dm³ nitric acid and 0.0500 mol/dm³ aqueous ammonia.
Relevant Equations:: Acid + Base = Salt + Water

This question is asking about finding the indicator. I think phenolphthalein will be used as there is a reaction between strong acid and strong base. Is this approach to the question correct? Or am I missing any important concept? Kindly tell
I could use some correction in case my thinking is wrong, but I would tend to agree here, to use phenolphthalein. Color change is at pH above 7 (but I not sure; I should really look-up this information). Full neutralization of ammonia would be at something above pH 7.
 

1. What is an indicator in acid-base titration?

An indicator is a substance that changes color in response to a change in pH. It is used in acid-base titration to determine the endpoint of the reaction, where the acid and base have completely neutralized each other.

2. How do I choose the right indicator for my acid-base titration?

The choice of indicator depends on the pH range of the titration and the color change of the indicator. A universal indicator can be used for a wide range of pH values, while specific indicators are more suitable for a narrow range. It is important to choose an indicator that has a color change close to the equivalence point of the titration.

3. Can I use multiple indicators in my titration?

No, it is not recommended to use multiple indicators in a titration as they may interfere with each other and give inaccurate results. It is best to choose one indicator that is suitable for the pH range of the titration.

4. What are some common indicators used in acid-base titrations?

Phenolphthalein, methyl orange, bromothymol blue, and litmus are some of the most commonly used indicators in acid-base titrations. Phenolphthalein is often used for titrations involving strong acids and bases, while methyl orange is used for titrations involving weak acids and bases.

5. Can I make my own indicator for acid-base titrations?

Yes, you can make your own indicator using natural substances such as red cabbage, turmeric, or beetroot. These indicators are sensitive to changes in pH and can be used for educational purposes. However, for accurate and precise results, it is recommended to use commercially available indicators.

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