What is uses of watch glasses?

Here are some common uses of watch glasses:

Weighing solids: Watch glasses can be used to weigh small amounts of solids, especially when using an analytical balance. The watch glass is placed on the balance, and the solid is added to the watch glass. The weight of the watch glass and solid is then measured. The weight of the solid is determined by subtracting the weight of the watch glass from the weight of the watch glass and solid.

Evaporating liquids: Watch glasses can be used to evaporate liquids, often in conjunction with a heating mantle or hot plate. The liquid is placed in the watch glass, and the watch glass is heated. As the liquid evaporates, the vapor escapes from the watch glass.

Covering beakers: Watch glasses can be used to cover beakers, flasks, or other glassware. This can help to prevent the evaporation of liquids from the glassware, and it can also help to keep dust and other contaminants out of the glassware.

Mixing liquids: Watch glasses can be used to mix liquids. The liquids are placed in the watch glass, and a stirring rod is used to mix the liquids.

Collecting precipitates: Watch glasses can be used to collect precipitates from chemical reactions. The precipitate is formed in a beaker or flask, and the watch glass is placed under the beaker or flask. The precipitate is then allowed to settle to the bottom of the watch glass.

Growing crystals: Watch glasses can be used to grow crystals. A solution is prepared, and the watch glass is placed in a warm, dust-free environment. The crystals will then grow on the watch glass.

Heating samples: Watch glasses can be used to heat samples. The watch glass is placed on the heating mantle or other heating device, and the sample is placed on the watch glass. The sample is heated slowly until the desired temperature is reached.