About Thermal Filtration What are the steps and precautions for thermal filtration?

Thermal filtration is heat conduction, i.e. at different temperatures.

when the temperature rises and falls

Thermal filtrationThermal filtration, a chemical experiment solid-liquid separation operation. There is a certain difference with "filtering while hot". Filtration while hot refers to the direct filtration of a warmer solid-liquid mixture using conventional filtration operations; Thermal filtration refers to the filtration process that uses instruments that are different from conventional filtration to keep the temperature of the solid-liquid mixture within a certain range.

Chinese name thermal filtration.

An operation to explain solid-liquid separation in chemical experiments.

Distinguish from filtering while hot.

From "Basic Chemistry Experiments".

Quick navigation. Instructions.

Thermal filtration is required if the solute in the solution tends to precipitate a large number of crystals when the temperature drops, and we do not want it to remain on the filter paper during the filtration process. —Basic Chemistry Experiments, Science Press, January 2008.

The funnel (hot funnel) method is used for operating thermal filtration.

The short-necked glass funnel is placed in a copper hot funnel filled with hot water to maintain the temperature of the solution. The neck of the glass funnel inside should be as short as possible, so as to avoid the solution staying in the funnel neck for too long during filtration, dissipating heat and cooling, and precipitating crystals to block the device.

Neckless funnel steam heating method.

Take a neckless funnel (ordinary glass funnel with the funnel neck removed) and place it above the water bath device to heat it with steam, and then filter it. The hotter funnel method is simple and easy.

The principle of filtration utilization is to use different particle sizes to separate.

The filtration operation is simply one stick, two low, and three leaning.

One sticker: the filter paper should be close to the inner wall of the funnel.

Two low: 1The filter paper should be lower than the edge of the funnel; 2.

The filtrate should be three times lower than the edge of the filter paper: 1The tip of the beaker "to be filtrate" is next to the glass rod; 2.

The glass rod is leaning against the three layers of filter paper (I can't understand why the filter paper has three layers, you can see that the long part of the end of this funnel is leaning against the inner wall of the beaker that "contains the filtrate".

Next, we explain in detail why it is necessary to achieve one stick, two low and three leaning.

In the filtration experiment, one sticker, two low, and three leaning are:

One sticker: the filter paper is close to the inner wall of the funnel, and there are no bubbles;

Two low: A The edge of the filter paper in the funnel is lower than the edge of the funnel mouth, and B The liquid level in the funnel is lower than the edge of the filter paper;

Three leanings: A When pouring liquid, the beaker is in contact with the glass rod, b the end of the glass rod is in contact with the three layers of filter paper in the funnel, and c the lower end of the funnel is in contact with the inner wall of the beaker that receives the filtrate

Therefore, the answer is: when filtering, the filter paper is close to the glass rod, no bubbles are left in the middle, the edge of the filter paper in the funnel is lower than the edge of the funnel mouth, the glass rod should be used to drain the liquid when pouring the liquid, the beaker is in contact with the glass rod, and the liquid level should not be higher than the edge of the filter paper, the glass rod is close to the three-layer filter paper, and the nozzle at the lower end of the funnel should be close to the inner wall of the beaker

1. It is not advisable to filter the colloidal precipitate and the precipitate with too small particles, because the colloidal precipitate is easy to penetrate the filter paper, and the precipitated particles are too small to form a dense precipitate on the filter paper, and the solution is not easy to penetrate.

2. When stopping the suction filtration, you need to unplug the rubber tube connecting the suction filter bottle and the pump, and then turn off the pump to prevent back-suction. In order to prevent the phenomenon of back-suction, a safety bottle is generally installed between the suction filter bottle and the pump.

The three reasons for filtering while hot are: under hot conditions, most solutes have a high solubility in solvents and can be completely dissolved. At the same time, under hot conditions, the viscosity of most solutions is reduced, the filtration resistance is small, and the filtration speed is accelerated.

The temperature is high, the solute is not easy to precipitate, and the separation effect is good.

1. Under hot conditions, most solutes have high solubility in solvents, so that they are completely dissolved.

2. Under hot conditions, the viscosity of most solutions is reduced, the filtration resistance is reduced, and the filtration speed is accelerated.

3. The sedan jujube line is effectively separated to remove insoluble impurities (mostly mechanical), or to separate from decolorizers (such as activated carbon), and solute precipitation may occur at low temperature, and the separation effect is not good. Whether organic or inorganic, there are common problems.

This thing, for example, is to be precipitated, and the impurities are dissolved in the solution, but if the temperature drops, the solubility will not be ground enough, and it will be precipitated and mixed in the precipitation. Lost its effect.

As a general rule, solutions with higher temperatures also have higher solubility and are not easy to crystallize. As a result, many processes require filtration at higher temperatures in order to increase the concentration of the solution and prevent crystallization from escaping. Some reagents generally deteriorate when the temperature drops.

Or no line swift method filtering.

The purpose of filtration while hot: according to the general law, the solubility of the solution with higher temperature is also higher, and it is not easy to crystallize. As a result, many processes require filtration at higher temperatures in order to increase the concentration of the solution and prevent crystallization from escaping.

Some reagents generally deteriorate when the temperature drops. Or it can't be filtered.

Filtration while hot is generally used for the purification of solutions with two (or more) solutes, since it is purification, there must be a target substance, and this target substance must have the characteristics of being greatly affected by temperature by the solubility of the file. Other substances are less affected by temperature and have lower or greater solubility.

Filtration refers to the operation of the liquid in the suspension penetrating the medium under the action of pushing force or other external forces, and the solid particles and other substances are intercepted by the filter medium, so that the solids and other substances are separated from the liquid.

Because a lot of substances don't have the same solubility when they're hot.

Thermal filtration will remove the unwanted stuff.

Hope. High school chemistry when to cool and filter when to filter while hot.

Crystals need to be collected and filtered with cooling, and samples that need to be collected are soluble in water and then cooled and crystallized need to be filtered while hot.

If you want to get a solute whose solubility is less affected by temperature, filter it while it is hot, and if you want to get a solute whose solubility is greatly affected by temperature, you can cool and crystallize.

University Chemistry Experiment: Why Filtering While It's Hot Can Filter Out Impurities.

University Chemistry Experiment: Why Filtering While It's Hot Can Filter Out Impurities.

Because the solubility of potassium chloride is less affected by temperature, there is no crystal precipitation in a hot saturated solution. [In the "hot filtration" operation, the main component of the filter residue is NaCl].

High School Chemistry Step 3: What to filter while it is hot and why to put a condenser tube on the device.

Filter while hot because the solubility of sodium thiosulfate varies greatly with temperature, with a solubility of 191g at 60 degrees and 71g at 20 degrees, which is a lot different. If you don't filter it hot, it will crystallize when you let it cool. Filtering again, the target product is also filtered out, reducing the yield.

The function of the condenser tube, here you have to understand the properties of sulfur powder to explain the condenser tube.

Sulfur powder is insoluble in water, and during the reaction, heating will promote the production of water vapor, which will also take away the sulfur powder. Don't be surprised that sulfur powder can be carried away by water vapor, right? There are always some finer particles in a pile of sulfur powder, which escape with the water vapor.

This condenser tube is a reflux tube, the steam is condensed and then returned to the reaction vessel, according to the structure of this balance, you can also guess that the reflux is to ** a reactant or product.

Both sodium sulfite and sodium thiosulfate are easily soluble in water, and they cannot run away when they evaporate. So guessing can also come out, is to ** sulfur powder, not to let it run.