The problem of chemical oxygen production in the third year of junior high school, and the three oxy

When the air is discharged upwards, the density is greater than the air and goes deep into the bottom of the bottle, because the gas with a density greater than the air always goes down, which is convenient to squeeze out the gas in the bottle and is easy to collect, if the density is smaller than the air, it will not penetrate into the bottom of the bottle.

When discharging air downward, the density is smaller than the air and goes deep into the bottom of the bottle, because the gas with a density smaller than the air always goes up, which is convenient to squeeze out the gas in the bottle and is easy to collect, if the density is greater than the air, it will not penetrate into the bottom of the bottle.

Understood

Exhaust method: Either up or down, go deep into the bottom of the bottle.

Drainage method: do not go deep, just at the mouth of the bottle.

Double tube: You don't need to memorize this, just observe the density of the incoming gas and the original gas or water in the bottle.

For example, when collecting oxygen, if there is air in the bottle, the long tube will take in the air and the short tube will come out (the oxygen will slowly sink and squeeze out the air above).

Hydrogen is collected, and there is air in the bottle, then the short tube intakes the air and the long tube discharges the gas (the hydrogen slowly floats up and squeezes out the air below).

If there is water in the bottle, it is a short pipe inlet and a long pipe out, because the density of water is much greater than that of gas.

Hello, the trachea must have a section of "rubber tube", so that it is easy to adjust.

1.If oxygen is collected by the upward exhaust method, the air duct must be deep into the cylinder

2.If the oxygen is collected by the drainage method, the trachea can be as deep as it goes

If the drainage method is used, the tube can not penetrate deep into the bottom of the bottle, first, it is easy to operate after the end of oxygen production, but to prevent the bottle from tipping over during the oxygen production process.

In the case of the upward exhaust method, it is necessary to reach the bottom to ensure that the collected oxygen is as pure as possible.

PS: In the air exhaust method, the density of the gas produced is greater than that of the air, so the upward air exhaust method is used, and the downward air exhaust method is used otherwise. However, regardless of the density of the gas produced, the tube must reach the bottom of the bottle in order to empty the air as much as possible, and the collected gas is pure. 】

Trust me ... The sad child who just got off the exam...

If the air exhaust method collects gas, the catheter extends into the bottom of the bottle, and the inspection is extended into the bottle, and the inspection is filled and placed at the mouth of the bottle!

It's that simple!

In general, the drainage method is used to produce oxygen, because the oxygen obtained by the air shooting method is not pure, after all, the oxygen and air density are close, and the drainage method does not need to extend the pipe to the bottom, and the air exhaust method is to extend to the bottom, whether it is the upward or downward air exhaust method

Depending on what equipment is used, the long-necked funnel has to go deep, and the separating funnel doesn't have to go deep.

Downward air exhaust method: the gas collector cylinder is placed upside down, and the conduit extends into the bottom of the gas collector cylinder;

Upward air exhaust method: the gas collection cylinder is being placed, and the conduit extends into the bottom of the gas collection cylinder;

Drainage gas collection method: fill the gas collection cylinder with water, put it upside down in the sink, and extend the conduit into the mouth of the gas collection cylinder.

Divided into the upward exhaust air method (the gas density is greater than the air) goes deeper.

The downward exhaust air method (gas density is less than air) goes deeper.

Drain gas collection (gas is not tolerant or insoluble in water) does not penetrate to remember.

Divide the drainage method and the air exhaust method, the drainage method does not need to go deep into the bottom of the bottle, and the upward air exhaust method goes deep into the bottom of the bottle

When the bottle is being released, the gas density is smaller than the air from the short in, and the density is greater than the air from the long in, that is, it is to go deep into the bottom of the bottle; When the bottle is placed upside down, it is the opposite of the top, the less dense one goes deep into the bottom of the bottle, and the denser one is at the mouth of the bottle.

The tube does not go deep into the bottom of the bottle when collecting oxygen by draining the oxygen, and the tube goes deep into the bottom of the bottle when collecting oxygen by the downward air method... I guess so.

When collected by the drainage method, the oxygen is insoluble in water and can not penetrate deeply, and in the exhaust method, the oxygen density is greater than that of the air.

The air exhaust method penetrates deep into the bottom of the bottle, either upwards or downwards. The drain method is placed on the mouth of the bottle.

The upward exhaust air method extends in, and the drainage method does not extend in.

The general drainage method collects oxygen deep into the bottom of the bottle.

It depends on the density of the gas compared to air.

That's what we're talking about: Denser than air, long in and short out, less dense than air, short in and out, I don't know, that's what you're talking about.

There are three common methods of producing oxygen in the laboratory: stool finishing.

1. Potassium chlorate to produce oxygen; 2. Potassium permanganate to produce oxygen; 3. Hydrogen peroxide to produce oxygen (the most common method in the laboratory). Oxygen, with the chemical formula O, relative molecular mass, colorless and odorless gas, is the most common elemental form of the element oxygen. Melting point, boiling point -183 .

Chemical formula: 2kClO3== (catalyst mNO2 written above the horizontal line) 2kCl + 3O2 (gas rising sign).

Advantages: High utilization.

Chemical formula: 2kmNO4== (reaction conditions: heating) K2mNO4 + MNO2 + O2 (gas rising sign).

Pros: No catalyst required.

Chemical formula: 2H2O2== (catalyst MNO2 is written above the horizontal line) 2H2O+O2 Advantages: no heating, environmental protection and energy saving.

Water – (direct current) hydrogen + oxygen.

Potassium permanganate – (heated) potassium manganate + manganese dioxide + oxygen potassium chlorate – (manganese dioxide, heated) potassium chloride + oxygen.

Hydrogen peroxide ---manganese dioxide), water + oxygen.

Sodium hydroxide + carbon dioxide – oxygen + sodium carbonate (this is uncertain).

On the first floor, sodium peroxide plus carbon dioxide produces oxygen and sodium carbonate, which seems to be a high school.

Potassium permanganate is heated to produce oxygen.

Key points of oxygen production in the laboratory: 1. The principle of preparation 2. The equipment of preparation 3. Precautions for preparation.

The principle of preparing oxygen in the laboratory (3), the device, the procedure, the collection method, the inspection method, the completion method and some experimental precautions.

Eight words: check, load, set, point, receive, interest, interest.

1. Heating potassium permanganate to produce oxygen Advantages: It can produce a relatively stable air flow, the reaction rate is moderate, and the danger is small. Cons:

The raw materials are high, the utilization rate of oxygen is low, the reaction device is complex, the improper operation is easy to cause the test tube to burst, and the solid waste has a negative impact on the environment.

2. Heating potassium chlorate + manganese dioxide Advantages: high utilization rate of oxygen element, no powder flying during decomposition. Cons:

The raw materials are high, the reaction device is complex, the improper operation is easy to cause the test tube to burst, the solid waste has a negative impact on the environment, and the prepared oxygen is mixed with more chlorine gas and has peculiar smell.

3. Hydrogen peroxide + manganese dioxide at room temperature Advantages: The two drugs can be placed in different containers during the reaction, and the reaction rate can be controlled by controlling the dripping rate of the liquid, which can make the reaction occur or stop at any time. The product is water, which is harmless to the environment.

Alcohol lamps are not used in the experiment, and the danger is small. Disadvantages: Low utilization rate of oxygen elements.

Heating potassium permanganate produces oxygen with a stable airflow and is the most commonly used method for producing oxygen in the laboratory.

Heating potassium chlorate + manganese dioxide The reaction per unit mass produces higher oxygen potassium manganate and higher hydrogen peroxide + manganese dioxide at room temperature.

In reactions with catalysts, the reaction rate may be too fast due to the amount of catalyst.

1. Heating potassium permanganate (the utilization rate of oxygen production is not high).

2. Heating potassium chlorate + manganese dioxide (general laboratory adopts annoying method).

3. Hydrogen peroxide + manganese dioxide at room temperature (expensive raw materials).

2kmNO4===K2mNO4+MNO2+O2 Excellent: more O2 is generated, lacking: heating is required, and the experimental phenomenon is not obvious.

MNO22KCLO3*****2KCl+3O2 Excellent: more O2 is generated, and Missing: Heating is required, and the experimental phenomenon is not obvious

MNO22H2O2====2H2O+O2 Excellent, the experimental phenomenon is obvious, the reaction is fast, and no heating is required Lacking: how much O2 is generated.