What is Titration technique:
Titration is a laboratory technique used to determine the unknown concentration of a solution by slowly adding a known concentration of another solution, called the titrant, until a chemical reaction is complete. The point at which the reaction is complete is called the endpoint, and the concentration of the unknown solution can be calculated from the volume and concentration of the titrant added. Titration is widely used in chemistry and biochemistry to determine the concentration of substances such as acids, bases, and proteins.
Types of Titrations
There are several types of titrations, including:
- Acid-base titration: This type of titration is used to determine the concentration of an acid or a base by reacting it with a solution of known concentration of the opposite type (an acid or a base). Indicators, such as phenolphthalein or universal indicator, are used to signal the endpoint of the reaction. Read our full Blog “Acid-Base Titration: How to Determine the Endpoint”
- Redox titration: This type of titration is used to determine the concentration of an oxidizing or reducing agent. Redox indicators such as potassium permanganate, potassium dichromate and iodine are used to signal the endpoint of the reaction.
- Complexometric titration: This type of titration is used to determine the concentration of a complexing agent. A complexing agent, such as EDTA, is added to the solution and the endpoint is indicated by a change in the color of an indicator.
- Precipitation titration: This type of titration is used to determine the concentration of a substance by causing it to form a precipitate. The endpoint is indicated by the appearance or disappearance of the precipitate.
- Non-aqueous titration: This type of titration is used to determine the concentration of a substance in a non-aqueous solvent. A suitable indicator is used to signal the endpoint of the reaction.
- Volumetric Karl Fischer titration: It is used to determine the amount of water in a sample. It uses Karl Fischer reagent as a titrant and the endpoint is indicated by a change in the electrochemical signal.
- Back Titration: It is a method of determining the amount of an analyte by reacting it with an excess of standard reagent and then back-titrating the excess with a secondary standard.
Procedure for Manual Titration:
- Gather all necessary materials and glassware’s, including a burette, flask, indicator, and solutions of the titrant and analyte.
- Clean and dry all glassware to ensure accurate measurements.
- Prepare a solution of known concentration, called the titrant, by measuring out a known volume or mass of the substance and dissolving it in a solvent. Make sure to accurately measure the concentration of the titrant solution. which will be added to the solution of unknown concentration, called the analyte.
- Measure a known volume or mass of the analyte solution into a container, called a flask.
- Add a few drops of an indicator to the analyte solution, which changes color when the reaction is complete.
- Fill the burette with the titrant solution and adjust the volume to zero by adjusting the stopcock.
- Stir the solution before starting the titration.
- Slowly add the titrant solution to the analyte solution using a burette,
- Continuously stir the solution while adding the titrant and observe the color change of the indicator.
- Record the volume of titrant added when the indicator changes color, this is the endpoint of the titration.
- Use the volume of titrant added and the known concentration of the titrant to calculate the concentration of the analyte solution.
- Repeat the process to obtain the average value of the concentration of the analyte.
Procedure for Titration Using Potentiometer (Autotitrator):
One of the most popular and accurate methods for performing titrations is using a potentiometer. A potentiometer is an electronic instrument that measures the electrical potential (or voltage) of an electrode. The principle behind titration using a potentiometer is that the potential of an electrode changes as the concentration of a substance in the solution changes. By measuring this potential, we can determine the endpoint of a chemical reaction, and thus the concentration of the substance in the solution.
There are several different types of electrodes that can be used with a potentiometer for titration i.e. Aqueous electrode, non-Aqueous electrode, Ag-ring electrode (Precipitation titration) etc. The most common type of electrode is the Aqueous electrode.
When performing a titration using a potentiometer, it is important to properly calibrate the instrument before starting the titration. Calibration is the process of measuring the electrode potential at known values, such as pH values for pH electrode, and adjusting the instrument to give accurate readings. This ensures that the instrument is able to accurately measure the potential of the electrode throughout the titration.
A titration using an potentiometer (autotitrator) involves the following steps:
- Prepare the solution to be titrated (the analyte) and the titrant (the solution of known concentration that will be added to the analyte).
- Connect the potentiometer to the analyte and titrant solutions.
- Prepare a method on Instrument or using software and set the desired titration parameter and endpoint of the titration on the Potentiometer.
- Choose the prepared method and begin the titration run.
- Titrant will be automatically added to the analyte until the endpoint is reached, as indicated by the Potentiometer.
- Instrument will automatically record the volume of titrant added and calculate the concentration of the analyte solution.
- Clean and maintain the potentiometer and electrodes.
Essential Precautions for Accurate Titration Results:
- Proper Calibration of Equipment: Ensure that all equipment used in the titration process, including the burette, pH meter, and balance, are properly calibrated before use.
- Controlled Temperature: Temperature changes can affect the accuracy of titration results, so it’s important to keep the room temperature consistent and to monitor the temperature of the solution during the titration process.
- Clean and Dry Equipment: Any impurities or residue on the equipment can affect the accuracy of titration results. Clean and dry all equipment thoroughly before and after use.
- Precise Measurement of Volumes: Use a calibrated burette or micropipette to measure the volumes of the reagents used in the titration process.
- Repeat the experiment: To increase the accuracy of the results, repeat the titration experiment a few times and calculate the average of the results.
- Avoid contamination: Keep the solution and reagents away from any source of contamination, that can affect the accuracy of the results.
- Use of Proper Indicator: Finally, it is essential to use the appropriate indicator for the type of titration being performed. Make sure that the indicator is fresh and that the endpoint is clearly visible. Using the wrong indicator or an expired one can lead to inaccurate results.
Thank you for reading my blog and I hope you found the information helpful.