Radiometric titrations

ANALYTICAL CHEMISTRY SEMINAR

RADIOMETRIC TITRATION

SUBMITTED TO SUBMITTED BY Dr. MUKTI VERMA MADAN LAL

TITRATION• Titration is a technique to determine

the concentration of an unknown solution.

• Titration is the slow addition of one solution of a known concentration (called a titrant or titrator) to a known volume of another solution of unknown concentration (called a titrand or analyte) until the reaction reaches neutralization, which is often indicated by a color change.

RADIOMETRIC TITRATION

When a titration involve radioactive reagent it is called radiometric titration.Radiometric titration is a quantitative method for the determination of an element.

•

Principle of radiometric titrationIn radiometric titration formation of a slightly soluble or readily removal compound by ion be determined with titrant.In this titration titrant is radioactive. When we Start titration, radioactive ion form a compound. As a result the activity of the titrant is reduce. At the end point we easily determine the concentration of radioactive ion

Elements of Titration . . . The standard solution: the

solution of known concentration. An accurately measured amount of standard solution is added during titration to the solution of unknown concentration until the equivalence or endpoint is reached.

The analyte: the solution of unknown concentration is known as the analyte. During titration the titrant is added to the analyte in order to achieve the equivalence point and determine the concentration of the analyte.

• The equivalence point: the point when the reactants are done reacting.The equivalence point is the ideal point for the completion of titration. At the equivalence point the correct amount of standard solution must be added to fully react with the unknown concentration.

• The end point: it indicates once the equivalence point has been reached. It is indicated by some form of indicator which varies depending on what type of titration being done. For example, if a color indicator is used, the solution will change color when the titration is at its end point.

• The calibrated burette: it is the main piece of equipment required for a titration method. Calibration is important because it is essential for the burette to be as accurate as possible in order to dispense very precise amounts of liquid into the sample.

A burette is a long cylindrical piece of glass with an open top for pouring in the titrant. At the bottom there is a carefully formed tip for dispensing.

Burettes usually have a plastic stopper that can easily be turned to deliver mere fractions of a drop of titrant, if needed. Burettes come in many sizes and are marked in millilitres and fractions of millilitres.

• The Indicator: the use of an indicator is key in performing a successful titration reaction. The purpose of the indicator is to show when enough standard solution has been added to fully react with the unknown concentration.  Indicators must only be added to the solution of unknown concentration when no visible reaction will occur. Depending on the solution being titrated, the choice of indicator can become key for the success of the titration.

CONDITION

Radioactive isotope is easily formed compound.

The activity of the titrant should be significantly change by the addition of other compound.

• The end point of the titration should have minimum or maximum activity.

• Titration does not favour the other compound formation, i.e; Side reaction is not possible.

• RMT should be form a less soluble or removal compound in the titration.

• TYPES OF RADIOMETRIC TITRATION

• There are four types of radiometric titration

• 1 Titration based upon Precipitate Formation.• 2 Titration based upon Complex Formation.• 3 Titration based upon Redox Reaction.• 4 Titration in Non-aqueous Media.

Precipitation RMT

In this titration radioactive indicator is precipitated and the end point is determine by the change in the activity of the solution of precipitates. The radiometric titration based on precipitate formation may contain two types of titration curves the shape of these curves will depend on whether the titrant, the test solution or both are labelled. The titration curves plotted against the volume of titrant and activity of precipitate are as follows.

end point

end point

Act

ivity

of P

reci

pita

te

Act

ivity

of S

uper

nant

Volume of Titrantvolume of titrant

Precipitation RMT

Complexometric RMT

Complexometric titrations works on the formation of a complex between the analyte and the titrant.

End point of this titration is also depend on the activity of the solution of complex. In these reactions the reacting species and the reaction products are in the same phase, before and after the reaction.

Therefore, these titrations can only be carried out by using auxillary method of seperation. solvent extration, paper chromatography, ion-exchange etc are some methods.

Complexometric titration:

• In general, they require specialized indicators that form weak complexes with the analyte.

• Common examples are Eriochrome Black T for the titration of calcium and magnesium ions, and the chelating agent EDTA used to titrate metal ions in solution.

Redox titration:• Redox titrations are based on a reduction-oxidation reaction

between an oxidizing agent and a reducing agent.

• A potentiometer or a redox indicator is usually used to determine the endpoint of the titration.

• Some redox titrations do not require an indicator, due to the intense color of the constituents.

• For instance, in permanganometry a slight persisting pink color signals the endpoint of the titration because of the color of the excess oxidizing agent potassium permanganate

• RMT in Non-Aqueous Medium

Non aqueous titration are those titration in which titration of weak acidic or basic substance carried out using non aqueous substance, to get end points.Such titrations can also be used for the titration of those substance which are not soluble in non aqueous solvents.

APPLICATION

• (a) Determination of the Composition of compound:

• During radiometric titrations, various compound are formed, their composition can be determined.

• (b) Investigation of Co-precipitation :

• In nuclear chemistry, Co-precipitation plays an important role, therefore its determination is extremely essential. Alimarin and Sirotina studied the Co-precipitation of silver, thalium and lead with iodide, thiocynate, sulphide using radioactive isotopes Tl240 Ag210 and Pb212

.

• (c) Determination of the specific activity of Radioactive preparations:

• Kametanietal have been studied the use of radioametric titration in the determination of specific activity of radioactive preparations.

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