The Titration Process
Titration is the process to determine the concentration of chemical compounds using the standard solution. The method of titration requires dissolving a sample with a highly purified chemical reagent, called a primary standards.
The titration technique involves the use of an indicator that will change the color at the end of the process to indicate that the reaction has been completed. The majority of titrations occur in an aqueous media, however, occasionally glacial and ethanol as well as acetic acids (in petrochemistry), are used.
Titration Procedure
The titration process is a well-documented, established quantitative technique for chemical analysis. It is employed by a variety of industries, including food production and pharmaceuticals. Titrations can be carried out manually or with the use of automated instruments. Titration involves adding a standard concentration solution to a new substance until it reaches the endpoint or the equivalence.
Titrations are conducted using various indicators. The most common ones are phenolphthalein and methyl orange. These indicators are used as a signal to indicate the conclusion of a test, and also to indicate that the base is fully neutralised. You can also determine the point at which you are with a precision instrument like a calorimeter or pH meter.
Acid-base titrations are by far the most common type of titrations. They are used to determine the strength of an acid or the concentration of weak bases. To do this the weak base must be transformed into its salt and titrated against a strong acid (like CH3COOH) or an extremely strong base (CH3COONa). In most instances, the endpoint is determined using an indicator, such as methyl red or orange. They change to orange in acidic solutions and yellow in neutral or basic solutions.
Another titration that is popular is an isometric titration that is typically used to determine the amount of heat created or consumed during the course of a reaction. Isometric titrations can take place by using an isothermal calorimeter, or with an instrument for measuring pH that determines the temperature changes of the solution.
There are a variety of factors that can cause failure in titration, such as inadequate handling or storage improper weighing, inhomogeneity of the weighing method and incorrect handling. A significant amount of titrant can be added to the test sample. To reduce these errors, a combination of SOP compliance and advanced measures to ensure integrity of the data and traceability is the most effective way. This will help reduce the number of the chances of errors occurring in workflows, particularly those caused by sample handling and titrations. It is because titrations can be performed on small quantities of liquid, which makes these errors more apparent as opposed to larger batches.
Titrant
The titrant solution is a mixture with a known concentration, and is added to the substance to be examined. The solution has a property that allows it to interact with the analyte to produce an controlled chemical reaction, that results in neutralization of the base or acid. The endpoint of the titration is determined when this reaction is complete and can be observable, either through color change or by using instruments like potentiometers (voltage measurement using an electrode). The amount of titrant dispersed is then used to calculate the concentration of the analyte in the initial sample.
Titration can be accomplished in various methods, but generally the titrant and analyte are dissolved in water. Other solvents like glacial acetic acid or ethanol can also be used to achieve specific purposes (e.g. Petrochemistry, which is specialized in petroleum). The samples have to be liquid for titration.
There are four different types of titrations - acid-base titrations; diprotic acid, complexometric and the redox. In acid-base tests, a weak polyprotic is being titrated using the help of a strong base. The equivalence of the two is determined using an indicator like litmus or phenolphthalein.
In labs, these kinds of titrations are used to determine the levels of chemicals in raw materials, such as oils and petroleum-based products. Manufacturing titrating medication use titration to calibrate equipment as well as monitor the quality of finished products.
In the food and pharmaceutical industries, titration is utilized to test the acidity and sweetness of food items and the moisture content in drugs to ensure that they have an extended shelf life.
Titration can be performed either by hand or using a specialized instrument called a titrator, which automates the entire process. The titrator has the ability to automatically dispense the titrant and monitor the titration for a visible reaction. It also can detect when the reaction has been completed, calculate the results and keep them in a file. It is also able to detect when the reaction isn't complete and stop the titration process from continuing. The advantage of using a titrator is that it requires less experience and training to operate than manual methods.
Analyte
A sample analyzer is a system of piping and equipment that extracts a sample from the process stream, alters it the sample if needed and then delivers it to the right analytical instrument. The analyzer is able to test the sample using a variety of concepts like electrical conductivity, turbidity, fluorescence or chromatography. A lot of analyzers add reagents into the sample to increase its sensitivity. The results are stored in a log. The analyzer is used to test gases or liquids.
Indicator
An indicator is a substance that undergoes a distinct visible change when the conditions in its solution are changed. The most common change is an alteration in color, but it can also be precipitate formation, bubble formation or temperature change. Chemical indicators can be used to monitor and control a chemical reaction such as titrations. They are commonly used in chemistry labs and are great for classroom demonstrations and science experiments.
Acid-base indicators are a common type of laboratory indicator used for testing titrations. It is composed of a weak acid that is paired with a concoct base. The base and acid are different in their color and the indicator has been designed to be sensitive to pH changes.
Litmus is a great indicator. It turns red in the presence acid and blue in the presence of bases. Other types of indicators include phenolphthalein, and bromothymol. These indicators are used to observe the reaction of an acid and a base. They are useful in finding the exact equivalent of the titration.
Indicators work by having an acid molecular form (HIn) and an Ionic Acid form (HiN). The chemical equilibrium that is created between these two forms is influenced by pH, so adding hydrogen ions pushes equilibrium back towards the molecular form (to the left side of the equation) and gives the indicator its characteristic color. The equilibrium is shifted to the right, away from the molecular base, and towards the conjugate acid when adding base. This produces the characteristic color of the indicator.
Indicators are most commonly used for acid-base titrations, but they can also be used in other kinds of titrations like Redox and titrations. Redox titrations are a bit more complex but the principles remain the same. In a redox test, the indicator is mixed with an amount of base or acid to adjust them. The titration is completed when the indicator changes colour in reaction with the titrant. The indicator is removed from the flask and washed to remove any remaining titrant.