Essential Laboratory Glassware and Tools: Function and Design

Burette: Precision Volume Measurement

The burette is a **glass device** used to measure volumes with high accuracy. It consists of a graduated cylinder marked from top to bottom in cm³ (milliliters). Its primary advantage is allowing the precise dispensing of liquid drop by drop, controlled by a **stopcock** (key) located at the bottom. This stopcock regulates the flow, making it essential for titrations.

Volumetric Pipette (Bulb Pipette)

These are long glass tubes featuring an **enlargement (bulb)** in the central part. The lower section is finished sharply. Volumetric pipettes are designed to measure and transfer a single, fixed volume of liquid with high precision.

Graduated Pipette (Measuring Pipette)

Graduated pipettes are narrow glass tubes of nearly uniform diameter throughout their length, ending in a fine point. They are used to measure variable volumes of liquid. **Warning:** Never pipette by mouth. They should also **not** be used as agitators.

Graduated Cylinder (Measuring Cylinder)

This laboratory tool is typically a straight glass tube of uniform diameter, graduated from top to bottom. The base is usually circular or hexagonal. Its accuracy is acceptable, but it is **less precise** than a pipette or a burette.

Separatory Funnel: Liquid Separation

This is an inverted, pear-shaped glass container featuring a small stopcock at the bottom center. Its function is to separate two immiscible liquids that have different densities. The denser substance is drained through the stopcock, which narrows into a thin tube, allowing for precise separation.

Erlenmeyer Flask (Conical Flask)

The Erlenmeyer flask is an elongated, conical flask with a flat bottom. It is designed to withstand heat, often used for preparing and heating solutions, provided the flame is separated by a wire gauze. It sometimes features approximate graduations for pouring liquids. It is commonly used in titrations, placed beneath the burette.

Kitasato Flask (Suction Flask)

This is a glass flask similar to a conical flask but features a side arm (output) near the neck collar. This side arm is used to connect a rubber hose to create a vacuum, often employed for filtration or for aspirating gases.

Beaker: General Purpose Container

The beaker is a cylindrical container made of resistant glass. It has many uses, such as preparing solutions. Beakers are available in many graduated sizes, depending on the required volume.

Watchglass: Covering and Weighing

A watchglass is a small, dish-like container used primarily to hold solid substances for observation or weighing. It can also be used to cover beakers or to transfer small amounts of solids.

Spatulas and Scoops

These are small utensils, often featuring a spoon-like shape on one end and a spatula on the other. They are used primarily for transferring or 'catching' solid chemical substances.

Wash Bottles

A wash bottle is a plastic container, shaped like a bottle, with a tube passing through the cap. It typically holds distilled water and is used to rinse laboratory material and prepare solutions.

Büchner Funnel: Vacuum Filtration

The Büchner funnel is typically made of porcelain and features a flat bottom with holes. It is used for filtration, especially for substances that are gelatinous or difficult to filter normally. A filter paper, slightly smaller than the base, is placed inside. Büchner funnels are usually placed atop a vacuum flask (like the Kitasato flask) for suction filtration.

Crystallizing Dish

This is a glass container that **should never be heated**. Solutions are poured into it and allowed to stand so that the solvent evaporates and the solute crystallizes.

Condenser (Reflux or Distillation)

A condenser is a glass tube assembly featuring two outputs and two internal tubes. A cooling substance (refrigerant, usually water) passes through one tube, while the substance being distilled (in vapor form) passes through the other. The refrigerant causes this vapor to cool and condense back into **liquid** form, which is collected via one of the outputs. This process is essential for distillation.