What do you need to produce oxygen, and how do you make it?

It is not necessary to use the drainage method, but it is also possible to use the upward exhaust method.

But the drainage collection method is better. The oxygen collected by the air exhaust method is not as pure as that collected by the drainage method because the relative molecular mass of oxygen is 32 while the average relative molecular mass of air is 29The two are similar, and when collecting by the exhaust method, it is easy to cause the air to be exhausted due to surrounding disturbances, and impurities in the air to be mixed into the oxygen.

Compared with the exhaust method, the oxygen collected by the drainage method is relatively pure, because the solubility of oxygen in the water is very small, which will not affect the collection, and it is easier to determine whether the collection is full. The disadvantage of the drainage method is that the operation is more troublesome, but considering the effect of the experiment, it is better to use the drainage method.

It is not necessary to use manganese dioxide as a catalyst, but if manganese dioxide can greatly speed up the reaction.

However, oxygen-containing substances must be selected as raw materials, because in this way oxygen can be produced.

1 No, it is also possible to use the upward air exhaust method, because oxygen is denser than air.

2 No, manganese dioxide only speeds up the reaction, and there is no oxygen production like him.

3 Yes, since the type of atom cannot be changed in a chemical reaction, it is necessary to choose a substance containing oxygen as a raw material.

It is also possible to use the upward exhaust air method.

If potassium permanganate is heated, manganese dioxide is not used.

Oxygen-containing substances must be selected as raw materials, otherwise where will the oxygen atoms come from.

Oxygen-containing substances must be selected as raw materials.

Before and after the chemical reaction, the element species remains the same.

Not necessarily with drainage.

Not necessarily manganese dioxide.

However, oxygen-containing elements must be used as raw materials.

Oxygen-containing substances must be selected as raw materials.

Heating potassium permanganate to produce oxygen step.

Oxygen production method: 1. Heating potassium permanganate: potassium permanganate generates potassium manganate, manganese dioxide and oxygen under heating conditions.

2. Separation of liquid air method.

Pressurized at low temperatures, the air is transformed into a liquid state, and then evaporated, because the boiling point of liquid nitrogen is 196, which is lower than the boiling point of liquid oxygen (183), so nitrogen first evaporates from liquid air, and the main thing that remains is liquid oxygen.

3. Membrane separation technology.

Membrane separation technology has developed rapidly. Using this technology, oxygen-rich air with a high oxygen content can be obtained by passing air through a membrane with oxygen-enriching function at a certain pressure. Using this membrane for multi-stage separation, oxygen-rich air with more than 90% oxygen can be obtained.

4. Molecular sieve oxygen production method (adsorption method).

Taking advantage of the fact that nitrogen molecules are larger than oxygen molecules, special molecular sieves are used to separate oxygen from the air.

First of all, the compressor is used to force the dry air to enter the adsorber of the vacuum through the molecular sieve, the nitrogen molecules in the air are adsorbed by the molecular sieve, and the oxygen enters the adsorbber, and when the oxygen in the adsorber reaches a certain amount (the pressure reaches a certain level), the oxygen valve can be opened to release the oxygen.

5. Catalytic decomposition of hydrogen peroxide solution: generation of water and oxygen.

1. Potassium permanganate to prepare oxygenDrug: potassium permanganate (dark purple solid), and manganese dioxide (black powder). The equation for the thermal decomposition of potassium permanganate is controversial because its decomposition products will vary under different temperature conditions.

<>2. Manganese dioxide and potassium chlorate are co-heated, and potassium chlorate (white solid) and manganese dioxide (black powder) are heated. The prepared oxygen contains a small amount of Cl2, O3 and trace amounts of ClO2; This method has been removed from some textbooks; The reaction is actually an exothermic reaction, not an endothermic reaction, and the above 1mol reaction occurs, and the exothermic reaction is 108kJ.

3. Catalytic decomposition of hydrogen peroxide solution, drug: hydrogen peroxide (H2O2) and manganese dioxide (black powder mnO2).

Precautions for the production of oxygen.

The experiment first checks the air tightness, and the test tube is tilted evenly by heating: "test tube tilting" means that when installing a large test tube, the test tube should be slightly tilted, that is, the test tube mouth should be lower than the bottom of the test tube, so as to prevent the small amount of water contained in the drug from becoming water vapor when heating, and condensing into water droplets at the nozzle and backflowing, resulting in the rupture of the test tube. "Evenly heated" means that the test tube must be heated evenly when heated.

Remove the catheter first and then move the lamp: It means that when the oxygen production is stopped, the dust must first withdraw the air duct from the water tank, and then remove the alcohol lamp If the alcohol lamp is removed first, the temperature in the test tube will decrease and the air pressure will decrease, and the water will be sucked along the catheter into the hot test tube, causing the test tube to rupture due to rapid cooling.

There are three reactions to produce oxygen in the laboratory, and the reaction principle is as follows:

Potassium chlorate is heat-decomposed into potassium chloride and oxygen under the catalysis of manganese dioxide

2kclo3=（mno2）2kcl+3o2↑

Potassium permanganate decomposes into potassium manganate, manganese dioxide and oxygen under heated conditions

2kmNO4 = (heating) K2mNO4 + MNO2 + O2

Electrolysis of water to produce hydrogen and oxygen:

2h2o=2h2↑+o2↑

Reaction principle: 1. Heating potassium chlorate to produce oxygen.

Generator and collection device: Same as the device used to heat potassium permanganate to produce oxygen.

Full: (Collected by drainage) If there are bubbles at the mouth of the gas collection cylinder, it means that the gas is full.

Collect with the upward exhaust air method) Place the spark-bearing strip at the mouth of the gas collector cylinder, if the spark-bearing strip rekindles, it means that the oxygen collection is full.

Inspection: Stick with sparks into the gas collection cylinder, if the sparks rekindle, it means oxygen.

2. Heating potassium permanganate to produce oxygen.

Generator: Since the reactant is a solid and the reaction needs to be heated, a device that heats the solid to prepare gas is selected.

Collecting device: Since oxygen is not easily soluble in water and does not react chemically with water, it is possible to choose a device that collects gas by draining water.

Since oxygen is denser than air and does not react chemically with components in the air, a device that collects gases by the upward exhaust method can be selected.

Steps: Check: Check the airtightness of the device.

Loading: Load potassium permanganate into a dry tube and place a ball of cotton at the mouth of the tube and tighten the tube with a rubber stopper with a catheter.

Fixed: Fix the test tube on an iron table.

Point: Light the alcohol lamp, and after the test tube is evenly heated, the alcohol lamp is fixed at the bottom of the test tube for heating.

Receiving: Determine the method of gas collection according to the selected collection device.

Shift: Remove the catheter from the sink.

Off: Extinguish the alcohol lamp.

Full: (Collected by drainage) If there are bubbles at the mouth of the gas collection cylinder, it means that the gas is full.

Collect with the upward exhaust air method) Place the spark-bearing strip at the mouth of the gas collector cylinder, if the spark-bearing strip rekindles, it means that the oxygen collection is full.

Inspection: Stick with sparks into the gas collection cylinder, if the sparks rekindle, it means oxygen.

Precautions: 1. When the reaction is stopped, the catheter should be removed from the sink first, and then the alcohol lamp should be extinguished to prevent the water in the sink from being sucked into the hot test tube and causing the test tube to burst.

2. When heating potassium permanganate, a ball of cotton should be placed at the mouth of the test tube to prevent potassium permanganate from being blown into the catheter and blocking the catheter.

3. Cotton should not be too close to potassium permanganate, otherwise it will lead to a generator**.

There are many methods to prepare oxygen in the laboratory, such as: potassium permanganate oxygen production, hydrogen peroxide (hydrogen peroxide), potassium chlorate decomposition (generally manganese dioxide as a catalyst), sodium peroxide reaction with water, etc. The specific teaching steps for oxygen production are as follows:

Prepare materials, including alcohol lamps, potassium permanganate, test tubes, iron frames, sinks, jars, etc.; Check the airtightness of the device, cover the test tube with your hand, put the catheter into the water, and see the bubbles coming out; Place the medicine, take an appropriate amount of potassium permanganate with the key, stretch it into the inside of the test tube, stand the test tube upright, put the medicine in, and stuff the cotton.

Place the medicine, take an appropriate amount of potassium permanganate with the key, stretch it into the inside of the test tube, stand the test tube upright, put the medicine in, and stuff the cotton. The alcohol lamp is heated, the test tube is preheated with an alcohol lamp, and then heated by an external flame, and the oxygen is collected by the drainage method; To test the oxygen, the water in the jar is drained, sealed with ground glass, and then the oxygen is tested with a small wooden strip with sparks, so that the oxygen preparation is completed.

Oxygen is a kind of elemental element formed by oxygen, the chemical formula O, its chemical properties are relatively active, and most elements can react with oxygen. It is not very active at room temperature, and it is not easy to interact with many substances. However, it is very active at high temperatures and can be directly combined with a variety of elements, which is related to the electronegativity of oxygen atoms second only to fluorine.

Oxygen production in the junior high school chemistry laboratory:

1.Heat potassium permanganate.

2kmno = k mno +mno +o (upward cluster arrow) 2Heat potassium chlorate and manganese dioxide.

2kclo = mno = 2kcl + 3o (or with the head of the upward arrow)3Decompose hydrogen peroxide.

2H O = MNO = 2H O + O (up arrow).