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Questions and Answers
What is the fundamental basis of precipitimetry as a method of analysis?
What is the fundamental basis of precipitimetry as a method of analysis?
- Ability of some ions to form a complex
- Ability of some ions to change color
- Ability of some ions to change state
- Ability of some ions to form a precipitate upon treatment with certain reagents (correct)
What is the condition for the precipitate in precipitimetry?
What is the condition for the precipitate in precipitimetry?
- The precipitate must be practically insoluble (correct)
- The precipitate must be highly soluble
- The precipitate must be completely soluble
- The precipitate must be partially soluble
What is the purpose of the solubility product rule?
What is the purpose of the solubility product rule?
- To determine the solubility of highly soluble salts
- To determine the solubility of sparingly soluble salts (correct)
- To determine the solubility of only acidic salts
- To determine the solubility of all types of salts
What happens when a sparingly soluble salt is shaken in water or other solvent?
What happens when a sparingly soluble salt is shaken in water or other solvent?
What is the general formula for the solubility product (Ksp)?
What is the general formula for the solubility product (Ksp)?
What is the significance of the solubility product (Ksp)?
What is the significance of the solubility product (Ksp)?
What is the condition for the formation of a precipitate according to the solubility product rule?
What is the condition for the formation of a precipitate according to the solubility product rule?
What is the importance of the end point in precipitimetry?
What is the importance of the end point in precipitimetry?
What is the effect of adding BaCl2 to a solution of BaSO4?
What is the effect of adding BaCl2 to a solution of BaSO4?
What is the effect of adding KCl to a solution of BaSO4?
What is the effect of adding KCl to a solution of BaSO4?
What is the effect of adding CN- to a solution of AgNO3?
What is the effect of adding CN- to a solution of AgNO3?
What is the effect of adding NH3 to a solution of AgCl?
What is the effect of adding NH3 to a solution of AgCl?
What is the common ion effect?
What is the common ion effect?
What is the diverse ion effect?
What is the diverse ion effect?
What happens when a sparingly soluble salt is dissolved in a solution containing a common ion?
What happens when a sparingly soluble salt is dissolved in a solution containing a common ion?
What happens when a sparingly soluble salt is dissolved in a solution containing a diverse ion?
What happens when a sparingly soluble salt is dissolved in a solution containing a diverse ion?
What is the purpose of adding excess AgNO3 in the first drop?
What is the purpose of adding excess AgNO3 in the first drop?
What is the role of KI in Denige's method?
What is the role of KI in Denige's method?
What is the color of the turbidity that indicates the end point in Denige's method?
What is the color of the turbidity that indicates the end point in Denige's method?
What is the advantage of using Denige's method over Liebeg's method?
What is the advantage of using Denige's method over Liebeg's method?
What is the formula of the complex formed by Ag+ ions with KCN?
What is the formula of the complex formed by Ag+ ions with KCN?
What is the purpose of using KCN in the reaction?
What is the purpose of using KCN in the reaction?
What is the minimum concentration of Ag+ required for AgCl to precipitate?
What is the minimum concentration of Ag+ required for AgCl to precipitate?
Why does AgI precipitate before AgCl?
Why does AgI precipitate before AgCl?
What is the term for the type of successive precipitation using the same precipitating agent?
What is the term for the type of successive precipitation using the same precipitating agent?
What is the purpose of a titration curve in precipitimetry?
What is the purpose of a titration curve in precipitimetry?
What determines the shape of the titration curve in precipitimetry?
What determines the shape of the titration curve in precipitimetry?
What is the significance of the inflection point on the titration curve?
What is the significance of the inflection point on the titration curve?
Why does a higher concentration of the precipitating agent and analyte result in a sharper end point?
Why does a higher concentration of the precipitating agent and analyte result in a sharper end point?
What is the effect of the solubility product of the precipitate on the sharpness of the end point?
What is the effect of the solubility product of the precipitate on the sharpness of the end point?
What is the product formed when silver is added to a solution containing cyanide ions?
What is the product formed when silver is added to a solution containing cyanide ions?
What is the purpose of adding more cyanide to a solution containing silver cyanide?
What is the purpose of adding more cyanide to a solution containing silver cyanide?
What is the end point of the precipitation reaction in argentometry?
What is the end point of the precipitation reaction in argentometry?
What is the medium required for the titration reaction in argentometry?
What is the medium required for the titration reaction in argentometry?
What is the indicator used in Mohr's method?
What is the indicator used in Mohr's method?
What is the reason for using a dilute solution of chromate in Mohr's method?
What is the reason for using a dilute solution of chromate in Mohr's method?
What is the condition required for the formation of a precipitate in argentometry?
What is the condition required for the formation of a precipitate in argentometry?
What is the limitation of Mohr's method?
What is the limitation of Mohr's method?
Study Notes
Precipitimetry
- Precipitimetry is a quantitative volumetric method of analysis based on the ability of some ions or compounds to form a precipitate upon treatment with certain reagents.
Conditions for Good Application of Precipitimetry
- The precipitate must be practically insoluble.
- Precipitation should be rapid.
- The end point must be easily detected.
Solubility Product Rule
- The solubility product rule controls the formation of precipitates and is applied only for sparingly soluble salts.
- For a sparingly soluble salt having the general formula AnBm, the solubility product will be: Ksp = [A-]n [B+]m, where Ksp is constant at constant temperature and pressure.
Factors Affecting Solubility of Sparing Soluble Salts
- Common ion effect: the presence of a common ion decreases the solubility of the sparingly soluble salt.
- Diverse ion effect: the presence of a diverse ion increases the solubility of the sparingly soluble salt.
- Complex formation: the formation of a complex can increase the solubility of the precipitate.
Titration Curves in Precipitation Reactions
- A titration curve is a plot of –log molar concentration of the precipitated ion versus ml of titrant.
- The sharpness of the inflection point on the curve determines the end point.
Fractional Precipitation
- Fractional precipitation is a type of successive precipitation using the same precipitating agent.
- The substance with the lower Ksp precipitates first.
Denige's Method
- Denige's method is a modification of Liebeg's method to render the end point more clear.
- It uses KI in an ammonical medium to detect the end point.
Applications of Precipitimetry
- Precipitimetry can be used for the determination of Cl- and Br-.
- The choice of method depends on the type of indicator used.
Mohr's Method
- Mohr's method is used for the determination of Cl- and Br-.
- The titrant is Ag+, and the indicator is chromate (concentration: 0.015 M).
- The end point is a brick-red color.
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Description
Learn about precipitimetry, a quantitative method of analysis based on the formation of precipitates upon treatment with certain reagents. Presented by Dr. Nada Samy.
