Watch glass facts for kids
A watch glass is a simple piece of laboratory equipment that looks like a round, slightly curved piece of glass. It's often used in science labs to hold small amounts of solids or liquids. Think of it like a tiny, clear saucer!
Contents
What is a Watch Glass?
A watch glass is made from special glass that can handle heat and chemicals. It's shaped like the glass cover on an old-fashioned pocket watch, which is how it got its name. These handy tools come in many different sizes, from very small to quite large.
What Does a Watch Glass Look Like?
Imagine a round, clear disc that's a bit curved in the middle. It's usually made of borosilicate glass, which is strong and resists breaking from heat changes. The edges are smooth and polished to make it safe to handle.
How is a Watch Glass Used in the Lab?
Watch glasses have many uses in a science lab. They are very versatile!
- Holding Solids: They are perfect for holding small amounts of solid chemicals, like powders or crystals. This keeps the chemicals safe and easy to see.
- Evaporating Liquids: If you have a small amount of liquid and want to let the water evaporate, you can spread the liquid thinly on a watch glass. The wide, shallow surface helps the liquid dry out faster.
- Covering Beakers: A watch glass can be placed on top of a beaker or flask. This helps to prevent splashes or to keep dust out of your experiment. It also lets gases escape if needed.
- Weighing Chemicals: Scientists often use a watch glass to weigh chemicals accurately on a balance. The watch glass holds the chemical, and its weight is subtracted later.
- Observing Reactions: Sometimes, a watch glass is used to watch a chemical reaction happen on a small scale. It's easy to see what's going on through the clear glass.
Why is it Called a Watch Glass?
The name "watch glass" comes from its shape. It looks very much like the glass cover that protects the face of an old pocket watch. These watches had a curved glass cover to fit snugly over the clockwork inside.
Caring for Your Watch Glass
Like all lab equipment, watch glasses need to be handled carefully. They should be cleaned thoroughly after each use to prevent contamination. They are usually washed with soap and water, then rinsed with distilled water and dried. Even though they are made of strong glass, they can still break if dropped.
Images for kids
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Caesium fluoride sample on a watch glass
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Crystal solids on a watch glass with folded paper above
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Front and back image of different sizes for watch glasses used in laboratory.
See also
In Spanish: Vidrio de reloj (química) para niños
