What is watch glass?

We explain what is the watch glass used in laboratories, what it is for and other features. In addition, other laboratory elements.

1. What is watch glass?

A laboratory instrument designed as a circular sheet of transparent glass is known as clock glass or clock glass . Its shape is concave-convex and its name comes from its resemblance to the glass that covered the face of the old pocket watches.

It is a frequent piece of laboratory, typically used in chemistry . It is often made of a mixture of metal and glass, in order to increase their resistance to 150 ° C of temperature .

2. What is watch glass for?

Watch glass has various uses in the laboratory. The most common is as a container of substances , to weigh or chew them, or to contain potentially corrosive or very hot substances. It is the ideal container to evaporate substances , because when it resists above the boiling point of water, it can be heated without fear of melting or destruction.

It can also be used as a lid or cover of a beaker , to allow the entry of air and the exchange of gases, while preventing the entry of dust into a substance that is needed pure and uncontaminated.

3. Watch glass characteristics

The watch glass is always round, of medium size and of a delicate nature, that is, fragile against mechanical impacts , despite its resistance to corrosive chemical agents or to relatively high temperatures. It is transparent, lightweight and more or less economical manufacturing.

4. Other laboratory instruments

Other common instruments in the laboratory are the following:

• Petri dish . Also known as “Plate” or “Box”, it is a round, transparent container with a cover of the same material, made of plastic or glass, and capable of closing but not hermetically. It is used for cell culture and contain specimens whose behavior you want to observe.
• Beaker . It is a thin cylindrical container, with a flat bottom and printed capacities along its height, ranging from 100 ml to several liters of capacity. It can be made of metal, borosicalated glass or plastic.
• Decanter blister . Also called the separating funnel , it is a glass container with a top plastic lid and a tap on the bottom, culminating in a tube. It serves, precisely, to decant substances. It has a transparent cone shape.
• Erlenmeyer flask . A glass jar with a wider body than its upper cylindrical mouth, the shape of which is useful for mixing by stirring, or to allow controlled evaporation of fluids. It is usually labeled on its side.
• Distillation flask . Also called a distillation balloon or Florentine flask, it is a bottle with a long neck and a spherical body, designed to allow uniform heating of substances and the reconduction of vapors. In its neck it usually has a lateral detachment tube, through which gases or vapors can be redirected.