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What is Titration? Definition, Formula, Preparation, Types

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  • Last Updated : 23 May, 2022

Titration is the gradual addition of a known concentration solution (called a titrant) to a known volume of an unknown concentration solution until the reaction approaches equilibrium, which is sometimes shown by a colour change. The titrant solution must satisfy the appropriate criteria to be used as a primary or secondary standard. Titration is a technique for determining the concentration of an unknown solution in a general way.

What is Titration?

Titration is a procedure that involves using a known concentration solution to determine the concentration of an unknown solution.

Titration, commonly known as titrimetry, is a chemical qualitative analytical technique for determining the concentration of an analyte in a mixture. Titration is an important technique in analytical chemistry, and it is also known as volumetric analysis.

Titration Formula

The formula for Titration is expressed as:

% Acid = (N × V × Equi. weight) × 100 / (W × 1000)

where,

  • N = Normality of Titrant,
  • V = Volume of Titrant,
  • W = Mass of the Sample,
  • Equi. weight = Equivalent weight of acid

Titration Procedure

Titration starts with the preparation of a titrant/titrator, which is a standard solution with a predetermined volume and concentration. This titrant is then allowed to react with the analyte until an endpoint or equivalence point is reached, at which point the analyte concentration can be estimated by measuring the amount of titrant consumed. Titration, on the other hand, is a stoichiometric technique used to determine a solution’s unknown concentration.

In terms of method steps, a highly exact amount of analyte is introduced to a beaker or Erlenmeyer flask. A little amount of the titrant (such as phenolphthalein) is placed beneath a calibrated burette or chemical pipetting syringe containing the indicator.

Small amounts of titrant are mixed into the analyte and indicator. This will continue until the indicator’s colour changes in response to the titrant saturation threshold. At this moment, it will show that we have reached the end of the titration. Essentially, the amount of titrant present during the reaction balances the amount of analyte present.

Techniques for Preparation

Both the titrant and the analyte must be in liquid (solution) form. To dissolve the solids, solvents such as glacial acetic acid or ethanol are utilized. To improve accuracy, concentrated analytes are additionally diluted. A steady pH is required or should be maintained during the reaction in the majority of non-acid–base titrations. To maintain the pH, a buffer solution is introduced to the titration chamber.

For particular conditions in the reaction chamber, a separate masking solution is occasionally introduced to eliminate the influence of the undesired ion. To accelerate the pace of some redox reactions, the sample solution must be heated and titrated while still hot.

Types of Titration

Acid-Base Titration

This is certainly the most significant sort of titration. Acidimetry is the measurement of acid strength using a standard solution of the base. Similarly, alkalimetry can be used to determine the strength of a base using a standard solution of an acid.

Both titrations undoubtedly contribute to alkali neutralization. In addition, in an acid-base titration, one solution is an acid and the other is a base. Furthermore, one is placed in a flask, while the other is placed in a burette and dripped into the flask until the titration reaches its endpoint. For Example: 

HA + BOH  →  BA + H2O

This titration is based on the neutralizing reaction between a base or an acidic and an analyte. In addition, a reagent is combined with the sample solution until it reaches the desired pH level. This type of titration is heavily reliant on the pH track or a pH meter.

Redox Titration

This titration is an example of an oxidation-reduction reaction. The chemical reaction in this titration occurs through the transfer of electrons in the reactive ions of aqueous solutions. One solution in redox titration is a reducing agent, while the other is an oxidizing agent. For Example:

  • Permanganate Titrations – Potassium permanganate is used as an oxidizing agent. It is kept in good condition by using dilute sulphuric acid.

MnO4 + 8H + 5e → Mn2++ 4H2O

Before the endpoint, this solution is colorless. Furthermore, potassium permanganate is used to calculate oxalic acid, ferrous salts, hydrogen peroxide, oxalates, and many other substances.

  • Dichromate Titrations – In an acidic medium, potassium dichromate is undoubtedly used as an oxidizing agent. Furthermore, the acidic medium is maintained by the use of dilute sulphuric acid.

K2Cr2O7 + H2SO4 → K2Cr2SO4 + H2O + 6O

  • Iodometric and Iodometric Titrations – Furthermore, during these titrations, free iodine is reduced to iodide ions and iodide ions are oxidized to free iodine.

l2 + 2e → 2l–                                …….. (reduction)

2l + 2e → 2e                      ……. (oxidation)

Precipitation Titration

This titration is based on precipitate production. In precipitation titration, we put two reacting chemicals into contact. For example: When silver nitrate solution is used, ammonium thiocyanate or sodium chloride solution is used. When it interacts, it produces a white precipitate of silver thiocyanate or silver chloride.

AgNO3 + NaCl → AgCl + NaNO3

 Complexometric Titration

The development of an undissociated compound occurs most importantly in this titration. It is also more than only precipitation titrations. For Example: 

Hg2+ + 2SCN → Hg(SCN)2

EDTA, or ethylenediaminetetraacetic acid, is an essential reagent that produces compounds with metals.

Sample Questions

Question 1: What is titrimetry?

Answer: 

Titration, commonly known as titrimetry, is a chemical qualitative analytical technique for determining the concentration of an analyte in a mixture.

Question 2: What are the techniques used for preparation?

Answer: 

Both the titrant and the analyte must be in liquid (solution) form. To dissolve the solids, solvents such as glacial acetic acid or ethanol are utilized. To improve accuracy, concentrated analytes are additionally diluted. A steady pH is required or should be maintained during the reaction in the majority of non-acid–base titrations. To maintain the pH, a buffer solution is introduced to the titration chamber.

For particular conditions in the reaction chamber, a separate masking solution is occasionally introduced to eliminate the influence of the undesired ion. To accelerate the pace of some redox reactions, the sample solution must be heated and titrated while still hot.

Question 3: What do you mean by redox titration and giving a reaction?

Answer:

This titration is an example of an oxidation-reduction reaction. The chemical reaction in this titration occurs through the transfer of electrons in the reactive ions of aqueous solutions. One solution in redox titration is a reducing agent, while the other is an oxidizing agent.

MnO4 + 8H + 5e → Mn2++ 4H2O

Question 4: Compute the titratable acidity if 19.5ml of 0.095N NaOH is required to titrate a 12ml sample of juice, the sum titratable acidity of that juice, articulated as the percentage of citric acid. ( let the molecular weight = 192 and the equivalent weight = 64)

Answer:

The formula for Titration is,

% Acid = (N × V × Equi. weight) × 100 / (W × 1000)

Therefore,

% acid = 0.095 × 19.5 × 64/12 × 10 

= 0.98%

Question 5: After titration, what unknown quantity can be calculated?

Answer: 

When performing titrations with an unknown, the purpose is to figure out what the unknown is. Calculating the unknown concentration and calculating the mass percentage of the unknown are both unknown numbers that can be calculated after titration.

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