what are test tubes used for

1 year ago 39

Test tubes are a common piece of laboratory equipment consisting of a finger-like length of clear plastic or glass tubing, open at the top, usually with a rounded U-shaped bottom. They are used for a variety of purposes in chemistry, biology, and medicine. Here are some of the main uses of test tubes:

Mixing and holding chemicals: Test tubes are widely used by chemists to hold, mix, or heat small quantities of solid or liquid chemicals, especially for qualitative experiments and assays.
Heating small amounts of liquids or solids: Test tubes are convenient containers for heating small amounts of liquids or solids with a Bunsen burner or alcohol burner. The tube is usually held by its neck with a clamp or tongs. By tilting the tube, the bottom can be heated to hundreds of degrees in the flame, while the neck remains relatively cool, possibly allowing vapours to condense on its walls.
Collecting and holding samples of physiological fluids: In clinical medicine, sterile test tubes with air removed, called vacutainers, are used to collect and hold samples of physiological fluids such as blood, urine, pus, and synovial fluid. These tubes are commonly sealed with a rubber stopper and often have a specific additive placed in the tube with the stopper color indicating the additive.
Culturing live organisms: Culture tubes are often used in biology for handling and culturing all kinds of live organisms, such as molds, bacteria, seedlings, plant cuttings, etc.; and in medicine and forensics to store samples of blood or other fluids. A test tube with a stopper is often used for temporary storage of chemical or biological samples.
Capturing gases: A test tube filled with water and upturned into a water-filled beaker is often used to capture gases, e.g. in electrolysis demonstrations.
Casual uses: Test tubes are sometimes put to casual uses outside of lab environments, e.g. as flower vases, glassware for certain weak shots, or containers for spices. They can also be used for raising queen ants during their first months of development.