Precipitation Titration: Overview, Questions, Preparation

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This chapter has multiple topics listed below:

Salt Hydrolysis Lewis Acids and Bases Precipitation Titration Arrhenius Acid Hydrocyanic Acid

Jasleen Taneja

Updated on Jun 4, 2024 15:57 IST

Table of Contents

Introduction
Use of Precipitation Titration
Types of Precipitation Titration
Precipitation Titration in Class 12
Illustrated Examples
FAQs on Precipitation Titration

Introduction

Titration is a chemical analysis procedure in which the quantity of a sample component is calculated by applying a precisely known amount of another material to the measured sample. The desired component interacts in a definite, known proportion.

Precipitation titration is a method of titration that requires the creation of a precipitate. The titrant reacts with the analyte in precipitation titration and forms an insoluble material, called a precipitate. The existence of a coloured precipitate will mark the first minor excess of silver ion (i.e., the endpoint). This can be done by using potassium chromate as an indicator. To form a precipitate (red) of silver chromate (Ag₂CrO₄), potassium chromate (K₂CrO₄) reacts with the first mild excess silver ion. Another process includes using an adsorption indicator; based on creating an adsorbed coating of silver indicator salt on the residue's surface, which forms in the presence of a strong silver ion.

Principle:

Quantity of added precipitating agent = The quality of a substance that is precipitated

Use of Precipitation Titration

It is used as a solvent for the determination of halide ions. It is used in food, drinks, and water to measure the salt content. Precipitation titration is used in many medications, such as carbromal, KCl infusion, infusion of NaCl, etc.

Types of Precipitation Titration

Volhard Process	Volhard's process includes the titration, bromides, iodides, and chlorides in an acidic atmosphere.
The technique of Fagan	This approach uses the reaction between the formed precipitate and the predictor. The measure used is dichlorofluorescein, a solution that functions as an anion.
Method selection	This method is used in a neutral solution to evaluate chlorides.

Precipitation Titration in Class 12

Precipitation titration is covered in detail in the chapter Equilibrium under ionic equilibrium. Precipitation titration is not a focused topic for the 12th boards, but you can expect questions from this topic in competitive exams.

Illustrated Examples

1. Which indicators are used in precipitation titration?

Answer: A small volume of potassium chromate solution is added to act as an indicator, a neutral solution of, say, chloride ions of silver nitrate solution. The chromate ions interact with silver ions at the endpoint to form the sparingly soluble, red, silver chromate.

2. What is the precipitation principle?

Answer: The precipitation technique entails creating a recognizable lattice from the combination of soluble antigen with its soluble antibody. When antigens and antibodies are at optimum concentrations (equivalence), it typically works better.

3. What is a precipitation reaction?

Answer: When two solutions that contain soluble salts are mixed, a precipitation reaction is the formation of an insoluble salt. The insoluble salt coming out of the solution is the precipitate. Precipitation reactions in the solution can help determine the identity of different ions.

FAQs on Precipitation Titration

Q: Is NaCl a precipitate?

A: A white precipitate develops when condensed HCl is applied to a saturated sodium chloride solution. The precipitate re-dissolves as water is applied to this mixture.

Q: Why does a precipitate form?

A: A precipitation reaction leads to the formation of an insoluble salt when two solutions containing soluble salts are mixed. The insoluble salt that comes out of the solution is known as the precipitate, hence, the reaction's name. Precipitation reactions in the solution can help determine the identity of different ions.

Q: What is an example of precipitation reactions?

A: An example of precipitation titration is the calculation of chloride ion concentration in a solvent by using silver ions from a known solution. The reactions are as follows: AgNO3 + Cl- = AgCl + NO3- (in NaCl solution).

Q: Is precipitate a chemical change?

A: The forming of a solid is another clue that a chemical transition has happened. A solid that divides after a chemical transition, from the solution, is called a precipitate. However, the substances produced during chemical changes cannot quickly switch back to the original substances.

Q: How is precipitation titration used in the industry?

A: Precipitation titration is seen in many industries. Halide (especially chloride) and silver determinations are the most significant applications.