Gravimetric and Volumetric Analysis are common methods used in analytical chemistry. They provide mechanism for determining the amounts of substances present in a sample, each with its own set of principles, advantages and applications. Let’s talk more about the them.
What is Gravimetric Analysis?
Gravimetric analysis is a quantitative method used to determine the amount of a substance present in a sample based on the measurement of mass. In this method, the target substance (the analyte) is usually precipitated from a solution as a solid compound of known composition. The solid precipitate is then isolated through filtration, washed to remove impurities, dried to remove moisture, and finally weighed accurately. From there, the amount of the analyte in the original sample can be calculated using stoichiometric principles.
Gravimetric analysis, a method of quantitative chemical analysis in which the constituent sought is converted into a substance (of known composition) that can be separated from the sample and weighed. The steps commonly followed in gravimetric analysis are:
- Preparation of a solution containing a known weight of the sample
- Separation of the desired constituent
- Weighing the isolated constituent
- Computation of the amount of the particular constituent in the sample from the observed weight of the isolated substance.
Gravimetric analysis is used in determining the concentration of ions in a solution, such as sulfate, chloride, or phosphate ions, by precipitating them as insoluble salts. It is a classical analytical technique with high accuracy and precision when performed carefully. This method requires attention to detail in experimental procedures, including controlling reaction conditions, filtering, washing, drying and weighing techniques.
What is Volumetric Analysis?
Volumetric analysis, also known as titrimetric analysis, is a quantitative method used to determine the concentration of a substance (analyte) in a sample by measuring the volume of a reagent (titrant) required to react completely with the analyte. The reaction between the analyte and the titrant is a chemical reaction of known stoichiometry, it allows the determination of the analyte’s concentration based on the volume of titrant added.
in other words, Volumetric analysis, is any method of quantitative chemical analysis in which the amount of a substance is determined by measuring the volume that it occupies or, in broader usage, the volume of a second substance that combines with the first in known proportions, more correctly called titrimetric analysis.
In volumetric analysis, the titrant is added gradually to the sample solution until the reaction reaches a specific endpoint, which is usually detected using a suitable indicator or by monitoring a physical change in the solution (such as a color change or precipitation). The volume of titrant required to reach the endpoint is proportional to the amount of analyte present in the sample.
Volumetric analysis is commonly used in acid-base titrations, redox titrations, complexometric titrations, and precipitation titrations. It is a relatively rapid analytical technique. It provides accurate and precise results when performed correctly. In general, Volumetric analysis finds application in fields like pharmaceuticals, environmental monitoring, food and beverage industries, and quality control in manufacturing processes.
Gravimetric vs Volumetric Analysis
| Basis | Gravimetric Analysis | Volumetric Analysis |
| Principle of Measurement | Measures the mass of a substance or a compound, usually through precipitation, filtration, and weighing. | Measures the volume of a solution of known concentration (titrant) required to react completely with the analyte. |
| Measurement Units | Provides results in units of mass (e.g., grams). | Analysis gives results in units of volume (e.g., liters or milliliters). |
| Sensitivity | More sensitive than volumetric analysis because changes in mass can often be measured with greater precision than changes in volume. | Has limitations in terms of sensitivity, especially if the endpoints of titrations are difficult to discern accurately. |
| Accuracy | Achieve high accuracy when conducted with careful control of experimental conditions. | Achieve high accuracy, but it may be affected by factors such as titrant concentration, endpoint determination, and human error during measurement. |
| Time Required | More time-consuming because it involves several steps, including precipitation, filtration, washing, drying, and weighing. | Can be relatively quicker, especially if automated titration methods are employed. |
| Applicability | Suitable for substances that can be precipitated quantitatively and for analytes present at relatively low concentrations. | Can be applied to a wide range of analytes and concentrations, provided suitable titrants and indicators are available. |
| Interference | Less susceptible to interference due to filtration | More prone to interference, especially with indicators. |
| Equipment Requirement | Requires precision balances, glassware for precipitation. | Requires volumetric glassware, burettes, and pipettes. |