Table of Contents
- 1 Why do we use two indicators in acid base titration?
- 2 Why is phenolphthalein a better indicator for titration than universal indicator?
- 3 How do you use pH to determine indicators?
- 4 How do you identify an appropriate indicator for an acid-base titration?
- 5 What is a suitable indicator for titration of CH3COOH and NaOH?
Why do we use two indicators in acid base titration?
In the titration of polyacidic base or polybasic acid there are more than one end point. One indicator is not able to give color change at every end point. So to find out each end point we have to use more than one indicator. It is because all indicator changes color on the basis of pH of medium.
Why is using more than one indicator needed to determine the pH of a solution?
By testing a solution with more than one indicator, with different color change regions, we can often narrow the pH to within a unit or so. Consider this example: A test solution turns blue when a small amount of litmus is added to it and stays colorless when thymolphthalein is added.
Why is universal indicator not suitable to use in a titration?
It’s used to determine the approximate pH of a solution. The universal indicator is a different color depending on the pH of the solution. So we wouldn’t normally use the universal indicator in a titration experiment because it changes color over a very wide pH range.
Why is phenolphthalein a better indicator for titration than universal indicator?
Now if you want to titrate to a certain pH-Value, it is easier to have an indicator like phenolphtalein that changes from colorless to a color at a certain point (phenolphtalein being colorless from 0 to 8 and red for <0). So you can titrate more accuratly to a certain pH-Value with specialized indicators.
Why do you need to use two indicators here?
To neutralize a strong acid with a weak base gives an acid salt and thus a pH on the acid side. Conversely a weak acid with a strong base gives an alkaline salt, so a pH on the alkaline side. Thus you may be instructed to use different indicators to give a colour change at the right point.
When using pH indicators What is the most accurate method to use to find a specific pH?
To find the specific pH of a sample, you will need a pH test paper or strip that is more precise than a litmus strip. More precise pH test papers or strips can give test results down to 0.2 pH units.
How do you use pH to determine indicators?
Starts here7:35WCLN – Using Indicators to Find Approximate pH – YouTubeYouTube
Why do you use an indicator in titration?
In a titration, you determine an unknown concentration of a sample by adding a second reactant of known concentration. In many titrations, you use a chemical called an indicator, which lets you know when the titration finishes.
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.
How do you identify an appropriate indicator for an acid-base titration?
An appropriate indicator for an acid-base titration will change colour at the same pH as the equivalence point of the acid-base reaction. That is, the endpoint of the titration as indicated by the indicator must be the same as the equivalence point of the acid-base reaction.
What is the difference between acid and base indicator?
Unlike most acids, however, the acid and base forms of indicators are different colors. Since the color of the indicator depends on the pH of the solution, indicators find wide use in applications that involve pH changes, such as titrations, pH testing, and science demonstrations.
What is the pH range of an indicator?
An indicator’s pH range is the range of pH values over which the indicator changes colors from its acid form to its base form. It extends from the highest pH at which only the acid form is visible to the lowest pH at which only the base form is visible.
What is a suitable indicator for titration of CH3COOH and NaOH?
A suitable indicator for the titration of the weak acid CH 3 COOH (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). Choosing an Appropriate Indicator for a Strong Acid – Weak Base Titration An aqueous solution of hydrochloric acid, HCl (aq), is a strong acid.