The problem of condenser tubes in the laboratory of distilled water in the third chemistry laborator

<>1. Wrong, cold water is "down in and up out", that is, from the condenser tube.

The lower end flows in and the upper end flows out.

2. You are doing the opposite, "up and down" can not make the water vapor be fully cooled, and "down in and out" can make the steam be fully cooled.

Reason: It is harder for water to flow up, and it is easier for water to flow down. The longer the cold water stays in the condenser tube as it flows up from the lower part of the condenser tube (the longer it takes to stay in the condenser tube than when the cold water flows down from the upper part of the condenser tube), and the longer the cooling time will of course allow the steam to be fully cooled.

3. Connecting the faucet to tap water, don't you do experiments directly to the faucet in the laboratory?

In this way, the steam in the pipe can be fully cooled, as long as the water continues to flow in from the lower mouth, it can flow out from the upper mouth, because the condenser pipe is double-layered.

1. The condenser tube is bottom-in and top-out.

2. If it is imported from above, because the gravity water will soon go out from the lower mouth, the time for heat exchange between water and steam will be shortened, and the condensation effect will be poor.

3. As long as there is pressure, it is fine.

1.The cooling water in the condenser tube is all down in and out of the pipe.

2.If you go up and down, you think about it, the water can't fill the condenser tube, and the steam can't cool enough.

3.You just connect the faucet to the rubber pipe and connect the water inlet - the water pressure provided by the faucet is enough to condense the water in and out of the pipe.

The water vapor is condensed and liquefied in the central pipe and flows out of the horn tube.

Cold water (faucet) on the periphery enters from the bottom and fully touches the hot steam pipe in the center to make the water vapor fully condensed.

If cold water flows down from above, some of the "hot steam pipes in the center" will not come into contact with the cold water, and the water vapor will not condense enough and will run away from the horn pipes.

The cooling water in the condenser tube enters from the bottom mouth and comes out from the upper mouth, in order to completely discharge the air in the condenser tube, so that the condensate can fill the entire condenser tube, so as to achieve the best condensation effect. If it goes up and down, the water flow will not be stored at all and fill the condenser tube, which will not have the condensation effect, and it is easy to damage the instrument, so that the local cold and hot will cause the condenser tube to rupture.

When distilled water is prepared in the laboratory, the temperature is distilled at the boiling point of the water at 100 degrees Celsius, and there is no need to use a thermometer to observe and control the temperature at any time, so there is no need for a thermometer.

There are two reasons why condensate water should go down and up for it:

1. If it goes up and down, it will only be concentrated at the lower end of the condenser tube due to the influence of gravity, and the air in the tube cannot be completely discharged, and the water cannot completely fill the condenser tube. Moreover, it will make the condenser tube hot and cold locally, and the cold mass will rupture the condenser tube due to uneven heating.

2. Underwater in and out, the inlet water is in contact with the low-temperature liquid, and the outgoing water is in contact with the high-temperature steam. It can ensure that the water at the lower end of the condenser tube is the water with the lowest temperature, so as to achieve the best condensation effect.

Summary. Because the condenser tube has cold water coming in and out of the upper mouth, then it has a process of filling in, and then the maximum condensation effect can be achieved.

Why in the distillation experiment, the cold water in the condenser tube enters from the bottom mouth and exits the upper mouth.

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Because the condenser tube has cold water coming in and out of the upper mouth, then it has a process of filling in, and then the maximum condensation effect can be achieved.

Plays a role in full condensation.

And if you go up from the bottom, it can completely fill the condenser tube with water, and then it will have a full condensation effect.

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1. The distilled steam is condensed into liquid, and after the hot air flow flows into the condenser tube, the temperature around the hot gas bright Zheng flow decreases under the influence of the cold water in the condenser tube, and the hot air flow fully condenses and liquefies into liquid droplets;

2. The droplets after the physicochemical of the liquid car key are collected after reflux;

3. To sum up, the condenser tube in the distillation device plays the role of condensation reflux.

In this way, the condenser tube can be filled with water, the inlet water is in contact with the low-temperature liquid, and the outlet water is in contact with the high-temperature steam to improve the cooling effect.

Two reasons:

1. If water enters the upper mouth, it will only be affected by gravity on the lower layer, so it will not completely fill the condenser tube.

2. Using the principle of counterflow, the water in the condenser tube has a cooling effect. When the water is heated, if there is a temperature difference in the water, the water will flow, the hot water will flow upward, and the cold water will flow downward, and the water will circulate and fully play the role of cooling. Therefore, during distillation, the water in the condenser tube should go down and up to allow the steam to fully liquefy.

The distillation unit uses a straight condenser tube, and the reflux device uses a spherical condenser tube.

Straight condenser tube.

It is composed of a straight glass tube that combines the inside and outside, and is mostly used for distillation operations, and the steam temperature is less than 140 degrees, and it cannot be used for reflux. On the upper and lower sides of its outer pipe, there are connecting pipe joints respectively, which are used to make water outlets and water inlets.

How to use: When using, connect the connecting port at the lower end to the faucet with a plastic pipe as the water inlet. The temperature of the water heated by steam is higher because the water temperature at the inlet is low; Hotter water automatically flows upwards as its density decreases, helping to circulate the cooling water.

Spherical condenser tube.

The inner tube is connected by several glass spheres for the reflux of organic preparations, suitable for liquids with various boiling points.

After long-term use, the rust in the spacer can be washed away with hydrochloric acid. Disadvantages: The condensed liquid is easy to get stuck in the glass ball after solidifying. Since the water pressure at the water inlet is high, the hose tends to fall off, so it is necessary to tie it with a wire when using.

Straight condenser tubes are generally used for distillation, i.e. when separating substances by distillation. The spherical condenser tube is generally used in the reaction device, that is, the spherical condenser tube is used to condense and reflux when considering the evaporation loss of reactants during the reaction, so that the reaction is more thorough!

Straight type for distillation and spherical type for reflux.

Because the spherical condenser tube is used to condense and reflux in consideration of the evaporation loss of reactants, it is necessary to enter from the lower mouth of the condenser pipe and exit the upper mouth.

Essentially, distilled water is not very different from other purified water, the only difference is the way the water is purified. Distillation is an ancient method of water purification. However, it is a relatively complex process that is difficult to do without a water distillation machine.

Distilled water: The water that is distilled and condensed, and the water that is steamed twice is called re-distilled water, and the water that is distilled three times is called three-distilled water. Distilled water can be divided into single and multiple times. After a distillation of water, the non-volatile components remain in the container and are removed, and the volatile components enter the initial fraction of the distilled water, usually only the middle part of the fraction is collected, accounting for about 60%.

To obtain purer water, alkaline potassium permanganate solution can be added to the primary distilled water to remove organic matter and carbon dioxide, and non-volatile acids can be added to make ammonia a non-volatile ammonium salt. Since glass contains a small amount of water-soluble components, it is necessary to use quartz distillation vessels to obtain very pure water when performing secondary or multiple distillations, and the resulting pure water should be kept in quartz or silver containers.

In order to prevent the evaporation and loss of reactants, a spherical condenser tube is used for condensation and reflux.

If the condensate is passed through the condenser pipe first, it is easy to cause the condensate pipe to rupture.

The principle is based on the separation of a two-component mixture. The liquid is heated to make it partially vaporized, the volatile components are enriched in the vapor, and the involatile components are also enriched in the residual liquid, which realizes the separation of the two components to a certain extent. The greater the difference in the volatile capacity of the two components, the greater the degree of enrichment described above.

In industrial distillation equipment, the partially vaporized liquid phase is in direct contact with the partially condensed gas phase for vapor-liquid interphase mass transfer, and the result is that the refractory components in the gas phase are partially transferred to the liquid phase, and the volatile components in the liquid phase are partially transferred to the gas phase, that is, the partial vaporization of the liquid phase and the partial condensation of the vapor phase are realized at the same time.

The molecules of the liquid have a tendency to overflow from the surface due to the movement of the molecules. This tendency increases with increasing temperature. If the liquid is placed in a closed vacuum system, the liquid molecules continue to overflow and form vapor at the upper part of the liquid surface, and finally the speed at which the molecules escape from the liquid is equal to the speed at which the molecules return to the liquid from the vapor, and the vapor maintains a certain pressure.

At this time, the vapor on the liquid surface reaches saturation, which is called saturated vapor, and the pressure it exerts on the liquid surface is called saturated vapor pressure.

Experiments have proved that the saturation vapor pressure of a liquid is only related to temperature, that is, the liquid has a certain vapor pressure at a certain temperature. This refers to the pressure at which the liquid is in equilibrium with its vapors, independent of the absolute amount of liquids and vapors in the system.

The role of condensate is to cool the steam and liquefy it into water. If you don't put in the condensate first, will some of the steam go out before it cools?