In the lab, knowing the equipment well and choosing it wisely is essential: this is part of good laboratory practice. It is a prerequisite in order to obtain reliable analysis results.

Among the equipment available in a chemistry lab, the glassware is very important. Several types of glassware exist.
The distinction is made between:

• Ordinary glassware: it provides very approximate information (order of magnitude) on the volume
• Precision glassware: it provides an estimate of the volume with more or less precision according to the glassware.

Regarding precision glassware, the distinction must be made between:

• Graduated glassware: it gives an estimated volume with limited accuracy
• Volumetric glassware: only this can provide a very precise measurement of volumes.

Furthermore, there is precision glassware to measure precise contained volumes (noted In) and precision glassware to measure precise delivered volumes (noted Ex).

In addition, depending on the level of precision of the glassware, there are two classes:

• class A glassware: the most accurate (tolerance
• class B glassware: tolerance twice as high as for class A (tolerance

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For some applications (e.g. with liquids that attack glass such as hydrofluoric acid), it is preferable to use plastic material instead of glass.

Several types of glass exist in glassware used in chemistry:

Standard glass: it is a soda-lime glass, made from silica SiO₂ (about 74%), sodium oxide Na₂O (13 %), lime CaO (7%), magnesia MgO (4%), and alumina (aluminium oxide) Al₂O₃ (2 %). As a result of its high coefficient of thermal expansion, this glass offers little tolerance to thermal shocks. It remains therefore seldom used for laboratory equipment intended for heating. However, it is easy to wet, and is therefore used widely for pipettes.

Borosilicate glass, very widely used in laboratories. This type of glass is acknowledged worldwide: ranked 3.3 DIN ISO 3585. It is made of silica SiO₂ (80 %), boric oxide B₂O₃ (13 %), and small amounts of alkalis (sodium oxide Na₂O potassium oxide K₂O: 4 %) and alumina Al₂O₃ (2.3%). Its thermal expansion is moderate, therefore its tolerance to thermal shock is good. Its chemical tolerance to acids (except FH and H₃PO₄ ) is also good – however it does not tolerate bases very well.

Pyrex (or Duran) glass, also widely used in laboratories: it consists in a borosilicate glass but strengened, with thicker sides. It provides a great robustness as well as an extraordinary tolerance to mechanical and thermal shocks.

20 mL: this is the total measurable volume
e.g. the glassware measures a delivered volume
+ 15 s: the volume is delivered in 15 seconds
20°C: the precise volume was measured at 20°C
+/- 0.03 mL: this is the uncertainty in the delivered volume
Class A: the most accurate glassware available

10: this is the total measurable volume (10 mL)
0.1: this is the level of graduations (0.1 mL)
B: precise glassware, but half as much as Class A
e.g. the glassware measures a delivered volume
20°C: the precise volume was measured at 20°C
+/- 0.10 mL: this is the uncertainty in the delivered volume
mL: this is the unit of volume