In acid-base titration, acids, and bases react with each other in a process called neutralization to form salt and water. This titration is generally used to find the amount of a known acidic or basic substance through acid-base reactions in the presence of an acid-base indicator or pH indicator. In neutralization titration, the analyte (titer – unknown molarity) react with the reagent (titrant – known molarity). Acid-base neutralization titrations are generally employed for quantitative analysis of most drug molecules and laboratory chemicals.
The analyte is prepared in a flask, by dissolving the substance being studied into a solution. A small amount of indicator is then added to the flask. The reagent is usually placed in a burette and slowly added to the analyte and indicator mixture. The amount of reagent used is recorded when the indicator causes a change in the color of the solution.
Acid: Acid is the substance whose solution turns blue litmus paper red. They have a sour taste (Examples: Vinegar contains 5-20% acetic acid and lemon juice contains citric acid). Acids react with most metals to form hydrogen gas (H2) and with baking soda to form carbon dioxide (CO2). All acid solutions conduct good electricity because acids form ions when dissolved in water.
Examples: Hydrochloric acid (HCl), Sulphuric acid (H2SO4), and Nitric acid (HNO3).
Base: It is a substance whose solution turns red litmus paper blue. They have a bitter taste and their solutions feel slippery like soapy water. All the solutions of bases also conduct good electricity because they too form ions in water.
Examples: Sodium hydroxide (NaOH), Potassium hydroxide (KOH).
Acidimetry: It is an acid-base titration method used to determine the concentration of acidic substances by titration with a standard base solution.
Alkalimetry: It is an acid-base titration method used to determine the concentration of basic substances by titration with standard acid.
Titrant: A substance or a reagent solution of precisely known concentration that is added in titration. It is generally filled in a burette.
Titer: A substance that is being analyzed in the titration, it is generally taken in a reaction flask.
Titration: The process, operation, or method used for finding out the concentration of a substance in solution by adding to it a standard reagent of known concentration until the reaction is complete. Usually, the completion of the reaction is observed by a color change or by electrical measurement and then by calculating the unknown concentration.
End Point: It is the point where the titration ends in practice, the point when the indicator color changes (usually the end of the titration).
Equivalence Point: The point when the number of equivalents mixed together is the same (in acid-base titrations equivalents refer to the number of moles of H+ and OH–). The Equivalence point is where the reaction is theoretically complete. It is also said to theoretical (or stoichiometric) endpoint.
Neutralization: A chemical reaction where an acid is reacted with an equivalent amount of base.
Titration Curve: Plot the pH of the solution as a function of the volume of titrant added.
Indicators: An auxiliary chemical compound that changes color and structure when exposed to certain conditions and therefore uses to detect the end point of the titration.
Example: Litmus is an indicator that becomes red in the presence of acid and blue color in the presence of base.
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