Testkärl

A testkärl, commonly translated as test tube, is a piece of laboratory glassware. It typically consists of a finger-like length of glass or plastic tubing, open at one end and closed at the other. Testkärl are primarily used in scientific experiments for holding, mixing, or heating small quantities of solid or liquid substances. They are a fundamental piece of equipment found in virtually all chemistry and biology laboratories.

The shape of a testkärl, with its narrow neck and rounded bottom, is designed to facilitate easy pouring and mixing. The narrow opening minimizes evaporation and contamination. They are often used in qualitative experiments where observations of reactions are made, such as color changes, precipitate formation, or gas evolution. Heating in a testkärl is usually done indirectly, often with a Bunsen burner or a heating block, and care must be taken to avoid direct heating of the bottom or rapid temperature changes.

Testkärl come in various sizes, ranging from a few milliliters to several hundred milliliters. They can be made from borosilicate glass, which is resistant to thermal shock and chemical corrosion, or from plastic materials like polypropylene, which are less prone to breakage. Special types of testkärl exist for specific purposes, such as graduated testkärl for approximate volume measurements or culture tubes for growing microorganisms. Their simple design and versatility make them indispensable tools in scientific research and education.