How to operate the air exhaust method, the downward air exhaust method

The air exhaust method is divided into the upward air exhaust method.

and downward air exhaust method, the former is suitable for the collection of gases that are much denser than air and are non-toxic; The latter is suitable for the collection of gases that are much less dense than air and are non-toxic.

The operation of the upward exhaust method: the gas collector cylinder is upright, the gas conduit is inserted into the gas collector cylinder close to the bottom but not in contact with the bottom, the mouth of the gas collector cylinder is covered with a glass sheet, and the remaining part is exported for testing the purity of the gas.

The operation of the downward air exhaust method: the gas collector cylinder is inverted, the gas conduit is inserted into the gas collector cylinder and close to the bottom but not in contact with the bottom, the mouth of the gas collector cylinder is covered with a glass sheet when collecting, and the remaining part is exported for testing the purity of the gas.

Extraction and collection of O2 with H2O2 and Mno2 is not suitable for the air exhaust method because the density of O2 is close to that of air, but the drainage method can be used.

A dispensing funnel can be prepared with a distillation flask.

H2O2 is placed in a separating funnel and Mno2 is placed in a distillation flask; H2O2 is dropped from the separating funnel into the flask, and the resulting gas is introduced into the sink through the catheter and then drained.

Gather. The advantage of this device is that the occurrence of O2 can be controlled.

As long as the return pipe is not blocked, the flowing water is unblocked, and there is no need for manual exhaust; There are two water pipes on this kind of car kettle, one is to feed water into the engine, and the other is the return pipe to the water tank or cylinder head, it should be noted that after adding enough water, do not screw the kettle lid immediately, start the engine, and wait until the water return pipe is flowing continuously, you can screw it on, if you tighten the kettle cover in advance, the air in the return pipe can not be discharged, the water in the system is not circulating, and it is easy to high temperature.

The downward exhaust method refers to the method used to collect gases whose density is significantly less than the density of air, such as hydrogen and ammonia. The following conditions do not apply: the gas is denser than or similar to air. e.g. n2(28); The gas reacts with the air components.

The principle of the downward exhaust air methodBecause the molecular weight of oxygen is less than 29, it is smaller than air.

According to Avogadro's law, the comparative density check calculates the formula quantity of gas, which can be seen as 29. The opposite of this is the upward exhaust method. Gases that do not react with air and have a large difference in density from air density can be collected by the air exhaust method, and the gas with a relative molecular mass greater than 29 is collected by the upward air exhaust method, and the gas with a relative molecular mass of less than 29 is collected by the downward air exhaust method.

How it works:Place the gas collector cylinder upside down on the bench with the neck pressed against the glass plate. The trachea is inserted into the gas collector cylinder, the gas is collected, and after the gas collector cylinder is full, the trachea is taken out and the coverslip is pressed tightly to seal the mouth of the bottle. When finished, the container is placed upside down on a level tabletop.

Depending on your problem, the methods of venting mainly include:

First, hot compress: you can use a towel to apply a hot compress or use an electric heater to speed up gastrointestinal peristalsis and help gas discharge.

Second, it can be exercised: such as jogging, brisk walking, and walking, it can promote gastrointestinal peristalsis and help gas discharge; In addition, you can also rub the abdomen in a clockwise direction with appropriate force with your hands to rub the belly button as the center, which can also help the discharge of gas.

Third, if the above ** effect is not good, it can be combined with drugs that promote gastrointestinal motility such as morpholine, which can help relieve stomach flatulence.

Fourth, eat more foods that have the effect of exhausting and promoting digestion in your daily diet, such as hawthorn, kumquat, orange, celery, white radish, and fennel. I hope my advice can help you.

The exhaust air collection method is divided into two types: the upward exhaust air collection method and the downward exhaust air collection method.

If the relative molecular mass of the gas is less than 29 (i.e., the gas density is less than the air density), then the downward exhaust air gathering method is used, and if it is greater than 29 (i.e., the gas density is greater than the air density), the upward exhaust air gathering method is used. Exhaust gas collection is the collection of gases that are easily soluble in water and do not react with components in the air, especially oxygen.

Non-polluting gases, which are usually denser than air and do not react with air, can be collected by the upward exhaust air method.

Such as: oxygen, carbon dioxide.

Non-polluting gases, which are generally less dense than air and do not react with air, can be collected by the downward exhaust air method.

Such as: hydrogen, helium.

The air inlet of the downward exhaust air method is at the upper end of the gas collection cylinder, and the air outlet is at the lower end of the gas collection cylinder, because the density of the gas collected by the downward exhaust air method is smaller than that of the air, so the collected gas fills the gas collection cylinder from top to bottom, and the air with high density sinks at the bottom of the cylinder. It is discharged from the air outlet at the lower end.

If there is pollution to the air, but the gas is not very polluting, it can also be collected in the ventilation kitchen by exhausting the air method. Such as: ammonia.

The advantage of the exhaust gas collection method is that the collected gas is drier, and the disadvantage is that the gas is not pure. Put the gas collector cylinder on the experimental table, the trachea is inserted into the gas collector cylinder upside down, collect the gas, the gas at the beginning is not pure oxygen, it takes a while to collect, when the inspection gas collector cylinder has been collected, take out the trachea, translate and push the glass piece, until the mouth of the gas collector cylinder is covered.

Upward air exhaust method: As the name suggests, the air is discharged upwards after the air is inhaled.

Timing of use: It is used when the density of the gas produced by the hand tomb is greater than the density of the air. Take oxygen, for example.

Reason: The gas produced is denser, so it is heavier than the carrying, and sinks under the gas collection cylinder, so the air is driven out from above.

Downward air exhaust method: As the name suggests, the air is discharged downward after the gas is introduced.

When to use: When the density of the prepared gas is less than the density of air. For example, ammonia.

Reason: The gas produced is less dense, so it is relatively light, and floats above the gas collection cylinder, so the air is driven out from below.

How to differentiate: When doing the problem, look at the density of the gas you are making and the density of the air. But how do we know how dense the gas is......Therefore, what gas is prepared by what method, the teacher will ask for hard memorization.

I hope the landlord likes it.