Go Science Crazy The Burette: A Vital Tool in the Chemist's Arsenal A staple of any chemistry lab, the burette stands as an essential tool for countless analytical procedures. This seemingly simple apparatus, consisting of a long, graduated glass tube equipped with a stopcock, plays a crucial role in accurately dispensing precise volumes of liquids, a vital function in various experiments and titrations.
Anatomy of a Burette The burette's design is characterized by its long, cylindrical body. Typically made of borosilicate glass for its durability and resistance to chemical attack, the burette features a uniform bore that allows for consistent flow of the liquid. Graduations etched along the body precisely mark the volume contained within the tube, allowing for accurate measurement with readings down to 0.1 mL. At the bottom, the burette terminates in a tapered tip, which facilitates controlled delivery of the liquid. This tip is connected to a stopcock, a precision valve that controls the flow of liquid dispensed. The stopcock's design varies, with options like PTFE plugs or glass keys offering different levels of control and resistance to chemical degradation.
The Burette's Role in Titrations Titrations are a cornerstone of quantitative analysis, allowing scientists to determine the concentration of an unknown solution by reacting it with a standardized solution of known concentration. The burette serves as the primary instrument for delivering the standardized solution to the reaction flask.
Here's how the burette functions in a typical titration: 1. Preparation: The burette is rinsed and filled with the standardized solution. The initial volume is carefully recorded. 2. Addition: The unknown solution is placed in the reaction flask alongside an indicator, a chemical that changes color when the reaction nears completion. 3. Titration: The stopcock is carefully opened, and the standardized solution is slowly dispensed into the reaction flask, while constantly stirring the mixture. 4. Endpoint: As the titration progresses, the indicator changes color, marking the endpoint of the reaction. 5. Calculation: The final volume dispensed from the burette is recorded. The difference between the initial and final volume indicates the volume of the standardized solution used, allowing for the calculation of the concentration of the unknown solution.
Applications Beyond Titrations While excelling in titrations, the burette's utility extends beyond this specific application. Its high precision in dispensing liquids makes it valuable for various tasks in chemistry and related fields, including: •
Preparation of standard solutions: Accurately measuring precise volumes of concentrated solutions for dilution to specific concentrations.