In the third year of junior high school, chemistry is related to the production of oxygen

When preparing oxygen, the test tube should be plugged with a rubber plug, and a section of the catheter should be put into water.

There are three types of laboratory preparation methods at the junior high school level.

1: Potassium chlorate and manganese dioxide are co-heated, 2kclo3 = heating = 2kcl + 3O22: heating potassium permanganate, 2kmNO4 = heating = K2mno4 + mno2 + O23: electrolyzed water, 2H2O = energized = 2H2 + O2

2H2O2 = MNO2 (catalyst) = 2H2O+O2 2kmNO4 = Heating = K2Mno4 + Mno2 + O2 2KCLO3 = Mno2 (catalyst) and heating = 2KCl + 3O22H2O = Energized = 2H2 +O2

It is prepared with potassium permanganate.

1: Heat potassium permanganate.

2: Electrolyzed water.

3: Potassium chlorate + manganese dioxide.

4: Hydrogen peroxide + manganese dioxide.

There are two ways to produce oxygen in the third year of junior high school:

1.Manganese dioxide is used as a catalyst to supply heat with KCLO4.

2.Hydrogen peroxide, catalyzed by manganese dioxide, releases oxygen.

There are three kinds: potassium permanganate, hydrogen peroxide, and potassium chlorate can be prepared separately.

2kmNO4==K2MNO4+MNO2+O2 (heating)2H2O2==2H2O+O2 (MNO2 is the catalyst)2KCLO3==2KCl+3O2 (MNO2 is the catalyst and needs to be heated), in addition, it can also be obtained by electrolysis of water.

1. Hydrogen peroxide plus manganese dioxide as a catalyst.

2. Preparation of potassium chlorate and potassium permanganate.

3. Electrolysis of water.

Manganese dioxide + hydrogen peroxide.

Heat potassium permanganate.

Manganese dioxide + potassium chlorate.

Drainage method.

It is necessary to grasp the raw materials, principles, equipment diagrams (generating devices and collection devices), inspection methods, precautions, etc.

This section includes three knowledge points: the laboratory preparation method of oxygen, the industrial preparation method of oxygen, and the test of oxygen. Knowledge is characterized by strong operability and some required knowledge, this knowledge should be combined with experimental operations

1 Laboratory Preparation of Oxygen:

1) Reaction principle: oxygen is prepared by decomposing hydrogen peroxide solution or heating potassium chlorate (white solid) or heating potassium permanganate (purple-black solid). When hydrogen peroxide or potassium chlorate is used, it is often necessary to add a catalyst – manganese dioxide (black powder).

3) Collection method: drainage method, upward air exhaust method.

Full inspection method: drainage method: when there are bubbles coming out of the mouth of the gas collection cylinder, it means that it is full. Upward air exhaust method: put the wooden strip with sparks close to the mouth of the gas collection cylinder, if the wooden strip is rekindled, it means that it is full, otherwise it is not full, continue to collect.

4) Operation steps: (take heating potassium permanganate to produce oxygen as an example).

Check: check the air tightness of the device; Packing: Fill the drug into the test tube and spread it flat on the bottom of the test tube; Fixed:

Fix the test tube on an iron stand; Point: Light an alcohol lamp for heating; Receiving: Collecting gases (by upward exhaust air method or drainage method); Off:

Evacuate the air duct from the sink; Off: Extinguish the alcohol lamp.

2. Industrial production method of oxygen: In industry, the separation of liquid air method is mostly used to produce oxygen. Here's how:

Pressurization at low temperatures transforms the air into liquid air, which then evaporates. Since the boiling point of liquid nitrogen is higher than that of liquid oxygen. The boiling point is low, so nitrogen evaporates first from the liquid air and the rest is mostly liquid oxygen.

In recent years, membrane separation technology has developed rapidly. With this technology, oxygen-rich air with 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 containing more than 90% oxygen can be obtained.

3 Oxygen test method: Extend the wooden strip with sparks into the gas collection cylinder, if the wooden strip rekindles, it means that the gas in the cylinder is oxygen.

1.A chemical equation for the production of oxygen in a laboratory

1.Heating potassium permanganate, the chemical formula is: 2kmNO4===K2mNO4+MNO2+O2

2.Potassium chlorate was heated with a catalyst MNO2 with the chemical formula: 2kClO3===Mno2)2kCl+3O2

3.Hydrogen peroxide (hydrogen peroxide) in the catalyst MNO2 (or red brick powder, potato, cement, rust, etc.), to generate O2 and H2O, the chemical formula is: 2H2O2===Mno2)2H2O+O2

2.Methods for producing oxygen in the laboratory

1. Hydrogen peroxide is catalyzed by manganese dioxide to produce water and oxygen.

Potassium 2 chlorate is heated under the catalysis of manganese dioxide to produce potassium chloride and oxygen.

3. Potassium permanganate is heated to produce potassium manganate, manganese dioxide and oxygen.

4. Water is electrified to produce hydrogen and oxygen.

h2o2==mno2===2 h2o+o2↑

KCLO3=== Heating mNO2===2 KCl+3 O2

kmno4===heating ===k2mno4+mno2+o2

h2o==energized==2 h2 +o2

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.

Hydrogen peroxide for oxygen production in the laboratory - junior high school chemistry experiment.

As soon as bubbles emerge, they are collected immediately, and the collected oxygen contains the air that is heated and expanded in the test tube (impure), so it is necessary to collect the gas when the bubbles are continuously and evenly released (at this time, the air has been exhausted and the oxygen that is continuously produced is released).

It should be collected only when the bubbles are evenly and abundantly popped out. If it is collected too early, the air in the device (test tube, air duct) is not cleaned, which may cause the collected oxygen to be impure.

It's not easy to collect, and according to what you said, I think there are probably two possibilities.

1. Failure to check the air tightness and gas leakage.

Second, the drug is not enough or the quality of the drug itself is not up to standard.

Third, there is not much reaction to catalyst poisoning.

Other gaseous impurities may be present and should not be collected until the air bubbles in the airway are evenly discharged.

The air in the reactor and pipelines should be discharged before it is collected!

1. Test tube, 2. Iron frame, 3. Alcohol lamp, 4. Collecting gas cylinder.

Mistake 1 The mouth of the test tube is facing up Mistake 2 Cotton is not stuffed Mistake 3 Use the bottle mouth downward venting method Mistake 4 The catheter that goes deep into the test tube is too long.

KMNO4=MNO2+2KMNO4=MMO2+K2MMO4 +O2 (Condition: Heating).

Instrument name: (1) Test tube (2) Iron frame table (3) Alcohol lamp (4) Gas collector cylinder Error: (1) The catheter protruding into the test tube is too long.

2) No lump of cotton is placed at the mouth of the test tube.

3) The tube is not slightly inclined downward.

4) The upward exhaust gas collection method or the drainage method should be adopted.

Chemical equation: KMnO4=mNO2+2KMNO4=mNO2+K2mNO4 +O2 (Condition: Heating).

Test Tube Iron Stand Alcohol Lamp Gas Collector Error: Apply alcohol external flame heating.

Oxygen should be vented upwards.

The mouth of the test tube should be inclined downward.

Stuff a ball of cotton at the mouth of the test tube.

The trachea should not actually reach into the tube.

Text expression: potassium permanganate (heating) —potassium manganate + oxygen + manganese dioxide 2kmno4 (heating) ==k2mno4 + mno2 + o2 I found five errors... You can refer to it.

1.Test tube.

2.: Iron stand.

3: Alcohol lamp.

4: Gas collection cylinder.

1) The catheter sticking into the tube is too long.

2) No lump of cotton is placed at the mouth of the test tube.

3) The tube is not slightly inclined downward.

4) The upward exhaust gas collection method or the drainage method should be adopted.

Chemical equation: kmno4 = mno2 + 2kmno4 = mno2

Test Tube, Iron Stand, Alcohol Lamp, Gas Collector Cylinder (2) Write out four errors in the figure:

The mouth of the test tube is slightly inclined downwards and the mouth of the gas collector cylinder is upward.

The catheter should be at the mouth of the test tube A piece of cotton should be placed in the test tube.

3) Please write the verbal expression and chemical formula of the reaction: 2kmNO4=K2MNO4+MNO2+O2

The heat and gas symbols are omitted from the equation.

(1) Test tube, iron frame, sprinkler lamp, gas collection cylinder.

2) 1) The mouth of the test tube should be slightly inclined downward.

2) The catheter only needs to protrude the rubber plug a little.

3) The catheter mouth can only be inserted near the mouth of the gas collection cylinder.

4) Drainage method collection or upward exhaust air method collection.

5) A piece of cotton should be placed in the test tube.

3) 2kmNO4 (heating) - K2mNO4 + MNO2 + O2 potassium permanganate (heating) = potassium manganate + manganese dioxide + oxygen.

(1) Test tubes, iron frames, alcohol lamps, and gas collection cylinders.

2) The mouth of the test tube should be slightly inclined downward.

The catheter should be just past the rubber plug.

The mouth of the gas collector cylinder should be placed upwards.

A ball of cotton should be placed at the mouth of the test tube.

3) Heating.

2kmno4 == k2mno4+mno2+o2

Test Tube Iron Rack Alcohol Lamp Gas Collector Cylinder The mouth of the test tube is tilted downward (to prevent the test tube from splitting).

Exhaust air or drain water upwards (O2 is heavier than water).

The catheter should be at the mouth of the test tube (to improve the purity of the collected oxygen) The mouth of the test tube should be plugged with cotton (the reason forgot).

External flame heating (heat saving).

2kmNO4 (heating) = K2mNO4 + MNO2 + O2 (gas).

Test tube.

: Iron stand. Alcohol burner.

Gas collection cylinders. 2) Write out the four errors in the picture:

The trachea in the generator is too long to protrude.

The large test tube orifice of the generating device is not slightly inclined downward.

There is no cotton at the mouth of the large test tube.

The air exhaust method is collected, and the gas collection cylinder is placed upside down, and there is no lid on the glass sheet.

3) Please write the verbal expression and chemical formula of the reaction

Potassium permanganate - heating - potassium manganate + manganese dioxide + oxygen ;

kmno4 k2mno4 mno2 o2

(1) Please write the name of the instrument:

Test tubes: Iron stand.

Alcohol burner. Gas collection cylinders.

2) Write out the four errors in the picture:

When the solids are heated, the tube mouth should be slightly downward.

The mouth of the test tube should be stuffed with a ball of cotton.

Because of the density of oxygen and the density of air, it should be used to exhaust the air upwards The air duct in the generator is too long.

3) Please write the verbal expression and chemical formula of the reaction

Potassium permanganate (heating) - potassium manganate + oxygen + manganese dioxide 2kmNO4 (heating) ==K2mNO4 + MNO2 + O2

The following figure is a diagram of the device used to heat potassium permanganate to produce oxygen in the laboratory, please answer the following questions: (1) Please write the name of the instrument: test tube, iron frame, alcohol lamp, gas collection cylinder.

2) Write out the four errors in the picture:

The catheter should be slightly inclined downward.

The catheter mouth that extends into the test tube should be at the mouth of the test tube.

The density of oxygen is greater than that of air, and the upward air exhaust method should be used A ball of cotton should be placed at the mouth of the catheter.

3) Please write the verbal expression and chemical formula of the reaction

Literal expression: potassium permanganate is generated under heating conditions of potassium manganate, manganese dioxide and oxygen;

Chemical formula: 2kmNO4===K2mNO4+MNO2+O2

Hydrogen peroxide, manganese dioxide, water + oxygen.

Potassium chlorate Manganese dioxide heating Potassium chloride + oxygen potassium permanganate heating Potassium manganate + oxygen + manganese dioxide Sorry, I can't hit the symbol of the arrow. And I'm probably at the same level as you, so that's all I've learned.

gas symbol).

Heating symbol) = 2kCl + 3O2 (gas symbol).

Heating symbol) = K2mno4 + O2 (gas symbol) + MnO2 electrolysis = 2H2 (gas symbol) + O2 (gas symbol) That's all I can think of.

MnO2 catalyzes or thermally decomposes hydrogen peroxide.

2H202 ==== 2H2O +O2 (Condition: MNO2) Potassium chlorate is pyrolytically decomposed by MNO2.

2kClO3 ==== 2kCl + 3O2 (Condition: Mno2, heated).

Prepared from potassium permanganate.

2kmNO4 = K2mNO4+MNO2+O2 (Condition: Heating).

2kmno4=k2mno4+mno2+o2↑2h2o2=mno2=2h2o+o2↑

2H2O = energized = 2H2 + O2

2kclo3=mno2, =2kcl+3o2 I think that's all for the third year of junior high school.

Heat 2kmNO4====K2mNO4+MNO2+O2MNO2

2h2o2*****=2h2o+o2

Heat 2kCl*****2kCl+O2

Heat 2HClL====2HCl+O2

Energized 2H2O*****2H2+O2