Chemistry Titration Techniques

Study Notes

Titration

Titration is a technique used to determine the concentration of a solution by measuring the volume of another solution needed to completely react with it.

Principles of Titration

Based on the complete chemical reaction between the analyte and the reagent (titrant) of known concentration.
Analyte: a solution of unknown concentration but known volume in a conical flask.
Titrant: a solution of known concentration in a burette.

Standard Solutions

Primary standard solution: extremely pure, highly stable, and can be weighed easily.
Secondary standard solution: less pure, less stable, and cannot be weighed easily.

Titration Process

Equivalence point: the theoretical point where the amounts of two reactants are just equivalent.
End point: the practical point at which the reaction is observed to be complete, usually detected with an indicator.
Indicator: an auxiliary substance that helps detect the completion of the titration process at the end point.

Acid-Base Titration

Involves a sample of unknown concentration of acid estimated with a known concentrated base or vice versa.
Strong acids and strong bases dissociate completely in water.
Example: determination of the normality of sodium hydroxide solution by a standard solution of hydrochloric acid.

Equipment and Materials

Glassware: burette, stand, conical flask, funnel, beaker, pipette, graduated cylinder, dropper, and washing bottle.
Materials: HCl solution (standard), NaOH solution (unknown normality), and phenol naphthalene indicator.

Procedure

Transfer 5 ml of unknown NaOH solution to a conical flask.
Add 2-3 drops of phenol naphthalene indicator.
Fill the burette with HCl solution to the zero mark.
Titrate NaOH against HCl until the color changes from colorless to pink.
Repeat the experiment three times and record the results.

Calculations

Calculate the average volume of HCl used.
Calculate the unknown concentration of NaOH using the average volume of HCl used.

Description

Learn about the technique of titration in chemistry where the concentration of a solution is determined by measuring the volume needed to react with another solution. Understand the principle of titration based on chemical reactions between the analyte and titrant of known concentration.