Laboratory Equipment

A burette (also buret) is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap, or stopcock, on the bottom. It is used to dispense known amounts of a liquid reagent in experiments for which such precision is necessary, such as a titration experiment. Burettes are extremely accurate: class A burettes are accurate to ± 0.05 cm3.

The precision of a burette makes careful measurement with a burette very important to avoid systematic error. When reading a burette, the viewer's eyes must be at the level of the graduation to avoid parallax error. Even the thickness of the lines printed on the burette matters; the bottom of the meniscus of the liquid should be touching the top of the line you wish to measure from. A common rule of thumb is to add 0.02 mL if the bottom of the meniscus is touching the bottom of the line[citation needed]. Due to the precision of the burette, even a single drop of liquid hanging from the bottom of a burette should be transferred to the receiving flask, usually by touching the drop to the side of the receiving flask. Through careful control of the stopcock and rinsing, even partial drops of liquid can be added to the receiving flask.

A Glass Beaker is a simple container for stirring, mixing and heating liquids commonly used in many laboratories. Beakers are generally cylindrical in shape, with a flat bottom. Beakers are available in a wide range of sizes, from one millilitre up to several litres.

They may be made of glass (very often borosilicate glass) or of various plastics. Beakers used for holding solutions of corrosive chemicals such as acids or other highly reactive chemicals, are often made of PTFE or other low reactivity materials. Beakers have a cylindrical shape, with flat bottoms so that that they can be set onto many different types of surfaces, and they usually have a thick top (lip) with a spout to make it easier to pour liquids.

Beakers may be covered, perhaps by a watch glass, to prevent contamination or loss of the contents. Beakers are often graduated—marked on the side with lines indicating the volume contained. For instance, a 250 mL beaker might be marked with lines to indicate 50, 100, 150, 200, and 250 mL of volume. The accuracy of these marks can vary from one beaker to another. The standard tall form graduated beaker is sometimes referred to as a Berzelius beaker.

A beaker is distinguished from a flask by having sides which are straight rather than sloping. The exception to this definition is a slightly conical sided beaker is called a Phillips beaker.