When evaporating a liquid with an evaporation dish, when is the best time to stop heating and why

Heating is stopped when a large number of crystals have precipitated. Because if it is evaporated, the solids will splash due to the high temperature.

It is better to heat it until the liquid is small. Because the residual heat of the alcohol lamp can be used to evaporate the rest.

Stop heating when there is a large amount of solid precipitation and stop stirring with glass rods to prevent splashing I got this experiment in the high school entrance examination The invigilation is very loose.

In fact, China requires a large amount of solid precipitation.

Because the heat of the crucible can evaporate the remaining liquid.

But in the English textbook I studied, I was asked to heat up half of the liquid.

Then let the crucible sit for a while. May 2, 3 days. It may be 1 week.

until the liquid has completely evaporated.

Simple! When a large amount of solids appears.

The evaporation dish can be heated directly. Evaporation dishes can be placed in asbestos mesh.

Use an alcohol lamp on it.

Or the gas lamp directly heats and evaporates, and then transfers it to a water bath to heat and evaporate when the solution becomes thicker. It should be noted that the evaporation dish should not be quenched after heating to prevent rupture.

An evaporation dish is a vessel that can be used to evaporate a concentrated solution. It can be heated directly on the tripod, or it can be heated indirectly by asbestos nets, water baths, etc., and when heated, it can be stirred with a glass rod.

Specifications: Commonly used specifications are centimeters and so on according to the size of the caliber. Different specifications can be selected according to different applications.

Evaporation dishes are porcelain products, and can also be made of glass, quartz, platinum or copper. Different materials and different corrosion resistance should be appropriately selected according to the properties of solutions and solids. It has good purity for the stability of acid and alkali.

It can withstand high temperatures, but should not be quenched.

The evaporation dish can be heated directly.

The evaporation dish is a vessel used to evaporate concentrated solutions or burn solids, with a large mouth and a shallow bottom, and there are two types of round bottom and flat bottom with handle. The evaporation dish is a vessel that can be used to evaporate the concentrated solution, which can be heated directly on the tripod with eggplant lead, or indirectly with asbestos nets, water baths, etc.

Since the evaporation dish is fired from clay, although it can be heated directly with an alcohol lamp, it usually needs to be preheated evenly first to prevent sudden thermal expansion and contraction and cracking. Erlenmeyer flasks, also known as triangular flasks, Ichsler flasks, Erlenmeyer flasks and Oroenmeier flasks, were invented by the German chemist Minhao Richard Ören Öhmann in 1861.

When heated, the evaporation dish is evenly heated by asbestos netting.

The equipment required for heating the shed branch inspection includes evaporation dishes, asbestos nets, alcohol lamps, tripods, matches, and wet rags. When heated, the objects in the evaporation dish are evenly heated by asbestos nets, alcohol lamps are used for heating, and tripods are used to support the evaporation dish. The asbestos mesh is composed of barbed wire and asbestos, the thermal conductivity of the wire is very good, because the wire mesh is very uniform, the iron wire can quickly and evenly transfer the absorbed heat to the heated object when heating, and the asbestos mesh disperses the grid-like heat to make the heat more evenly transferred to the heating device.

What is the main function of asbestos netting? How does it work? What are the precautions?

1. Main function: to make the object evenly heated. Asbestos nets are often used in chemical experiments, mainly for heating liquids on the tripod of alcohol lamps.

Because the flame is concentrated somewhere in the container for a long time, it will cause the container to burst. Asbestos is not a flammable substance, it can disperse the heat of the flame into the air, and the heat of the flame will be dispersed to every corner of the container in separate chains, and the container will not burst if burned for a long time.

2. How to use: The asbestos net is used to heat the object evenly when heating, so as not to cause local high temperature and protect the instrument from being exploded. Asbestos mesh is made of square barbed wire with asbestos wool glued to the upper part of the middle. The commonly used specifications are 125 125mm.

3. Precautions: Do not contact with water, so as not to fall off the asbestos or rust the iron mesh; The asbestos net should be handled gently to avoid falling off the asbestos lint due to the impact of hard objects; It is strictly forbidden to fold.

1. Can the evaporation dish be heated directly?

2. Can the test tube beaker evaporation dish be heated directly?

3. When evaporating and crystallizing, can the evaporation dish town orange be carefully heated directly?

4. Can the evaporation dish be heated directly and why?

1.An evaporation dish is a vessel that can be used to evaporate a concentrated solution, which can be heated directly on a tripod or indirectly with an asbestos net or water bath.

2.Since the evaporation dish is fired from clay, although it can be heated directly with an alcohol lamp, it is usually necessary to preheat it evenly first to prevent sudden thermal expansion and contraction and cracking.

Can be heated directly on a tripod. An evaporation dish is a vessel that can be used to evaporate a concentrated solution and can be heated directly on a tripod. It can also be heated indirectly with asbestos nets, water baths, etc., and when heated, it can be stirred with glass rods.

Commonly used specifications are centimeters and so on according to the size of the caliber.

Notes:1) It can withstand high temperature, and cannot be quenched after heating to prevent breakage.

2) The evaporation dish should be taken and placed with crucible pliers, and fixed with a tripod or iron frame table when heating.

3) When the amount of liquid is large, it can be heated directly, and the small amount or viscous liquid should be heated by asbestos net or placed on the mud triangle.

4) When heating the evaporation dish, stir continuously with a glass rod to prevent the liquid from splashing around when it is partially heated.

Didn't get to the point! There are also more heat-resistant varieties of beakers, but because of their high walls, which hinders the escape of water vapor, the evaporation effect is not as good as that of evaporation dishes.

No, because the beaker is flat-bottomed and cannot be heated directly, the evaporation dish can be heated directly.

After the solid appears more, the glass is heated unevenly, and the possibility of explosion is great, so the evaporation dish is used, which is determined by the thermal conductivity coefficient and thermal expansion coefficient of the material!

The evaporation dish has a large opening, which can evaporate the water relatively quickly and obtain the desired solid substance.

The heating area of the evaporation dish is large, and the ceramic products are resistant to high temperature and have good thermal conductivity.

Beakers are thin, not resistant to burning, and prone to breakage.

At the secondary level, the evaporation dish is the only instrument used to evaporate crystallization.

Although beakers can generally be heated, be careful not to dry boil them when heating them evenly, and it is best not to dry boil.

When the liquid is heated, do not exceed 2 3 of the beaker volume, and generally 1 2 of the beaker volume is suitable for the beaker to be used as a reaction vessel for preparing solutions, dissolved substances and larger amounts of substances at room temperature or under heating conditions.

Attention should be paid to the use of beakers;

1. When heating the beaker, put an asbestos net on it to evenly heat the heat. The beaker can not be heated directly with a flame, because the bottom surface of the beaker is large, and it can only be burned to a part with a flame, so that the glass is heated unevenly and causes explosion.

2. When heating, wipe the outer wall of the beaker dry.