18 Questions
Which titration uses the appearance of a precipitate as the endpoint detection method?
Titration of Cl- and Br- by AgNO3
In Mohr's method, the medium must be neutral or slightly alkaline to prevent the conversion of chromate into what?
Dichromate
In Fajan's method of endpoint detection in precipitimetry, what is used?
Adsorption indicators
In Fajan's method, when are acidic dyes preferentially adsorbed by the precipitate at the equivalence point?
Titration of AgNO3 with chloride or bromide ion
In Fajan's method, when are basic dyes preferentially adsorbed by the precipitate at the equivalence point?
Titration of CN- with Ag+
What type of indicator is used in Fajan's method of endpoint detection in precipitimetry?
Adsorption indicators
In Fajan's method, which type of dye is preferentially adsorbed by the precipitate when titrating AgNO3 with chloride or bromide ions?
Acidic dyes
What is the purpose of the adsorption indicators used in Fajan's method?
To change color when adsorbed by the precipitate at the equivalence point
Which of the following is a requirement for the successful use of adsorption indicators in Fajan's method?
The indicator dye ion must be opposite in charge with the precipitating titrant ion
In Mohr's method, what is the required medium for the titration?
Neutral or slightly alkaline medium
Which method is used to titrate Ag+ by CN-?
Lang's method
Which method is used to determine Cl- and Br- by AgNO3 using chromate ion as an indicator?
Mohr's method
Under which pH conditions are weak acidic dyes, such as fluorescein, used in Fajan's method?
Slightly acidic
Which dye can be used at pH 4 in Fajan's method?
Fluorescein
Why can't eosin be used for Cl determination in Fajan's method?
It has no opposite charge to the precipitating titrant ion
True or False: One of the requirements for the successful use of adsorption indicators in Fajan's method is that the indicator dye ion must have the opposite charge to the precipitating titrant ion.
True
True or False: Basic dyes are used in Fajan's method in an acidic medium to ensure their ionization.
False
True or False: Eosin can be used for Cl- determination in Fajan's method.
False
Test your knowledge on Fajan's method and dyes used in different pH conditions. Questions cover the use of weak acidic dyes like fluorescein, pH conditions for specific dyes, and limitations of certain dyes in the method.
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