Evaporation tray
The evaporation dish is a laboratory device for heating solutions . It usually consists of porcelain , ceramic or glass. Evaporation dishes are used to evaporate excess water - or another solvent - so that a concentrated solution or the substance dissolved in it remains. This process is also called narrowing in technical terms .
In addition to the usual white, there are also black evaporation trays for schools in order to better show a white residue.
The shape of the evaporating speeds for three reasons the evaporation :
- The shell is shallow or semi-deep. A relatively large liquid surface favors evaporation.
- When heated in a flask or beaker, some of the steam condenses on the walls of the vessel and flows back into the solution. That is not possible here.
- Due to the open shape, the steam is transported away even with a slight draft.
The heating of a liquid in an evaporating dish must be carried out with extreme care, as the low walls encourage splashing. Evaporation dishes are hardly suitable for stirring or swirling liquids. For evaporation in the laboratory, a rotary evaporator is usually preferred today because it works much faster and often allows the use of a negative pressure or a vacuum . Delayed boiling also occurs less violently than with other laboratory devices.
Individual evidence
- ^ Gerhard Meyendorf: Laboratory equipment and chemicals . People and knowledge Volkseigener Verlag, Berlin 1965, pp. 11–12.