Junior High School Chemistry Laboratory Oxygen 3

Filter residue. Because manganese dioxide is a catalyst, it does not react when the catalyst is made.

2mol hydrogen peroxide gives 2mol of water and 1mol of oxygen. The reaction to the gas, i.e., oxygen, is, then according to the ratio of stoichiometric numbers, the molar amount of hydrogen peroxide can be obtained as , i.e., , and therefore, its mass fraction is.

Filter Residue Quality:2h2o2 = 2h2o + o2

x

Solution: x=

Hydrogen peroxide mass fraction:We'll be happy to answer for youSatisfied (give a good review).

Hello. Manganese dioxide is a catalyst and is not consumed)

Oxygen = hydrogen peroxide.

Hydrogen peroxide. Answer percent.

1)2)（1）

The reduced mass is the mass of the overflowing oxygen.

2) the amount of oxygen in the substance).

2 h2o2 = 2h2o+ o2 ↑

2*The quality score is:

The filter residue is manganese dioxide, and manganese dioxide is not reacted as a catalyst).

Oxygen: hydrogen peroxide = 1:2 m (hydrogen peroxide) =

Mass Score =

Manganese dioxide quality is ignored and it is filter residue.

1. Water is divided into 2 H2O energized under the action of direct current 2H2 + O2 2, hot potassium permanganate: 2kmNO4 heated K2mNO4 + Mno2 + O2

3. Heating potassium chlorate (with a small amount of manganese dioxide): 2kclo3 ==2kCl + 3 O2

4. Hydrogen peroxide decomposition reaction under the condition of manganese dioxide as catalyst: H2O2 mNO22H2O+ O2

5. Experiment to study the composition of air 2HGO heating HG+ O2 commonly used in the laboratory to produce oxygen

1. The cost is too high, 5. Mercury is toxic.

2h2o2 = (mno2)2h2o+o2 (up arrow).

2kClO3 = (mNO2) (heated) 2kCl + 3O2 (upper arrow cover).

2kmno4 = (heating cheats) k2mno4 + mno2 + o2 (upper arrow rent stuffy makeover).

Reaction equation: kmno4 k2mno4+mno2+o2 1. Check the air tightness.

Tuck the rubber stopper tightly.

The catheter is placed in water.

Warm the tube lightly with the palm of your hand.

The principle of thermal expansion and cold contraction is used. The gas expands when heated to form bubbles, and shrinks when cold to form a water column.

2. Loading medicines.

Dispense the powdered solid with a medicine spoon.

Feed the bottom of the tube with a paper tray.

Upright tubes. Avoid solid chemicals sticking to the nozzle or wall of the tube.

3. a connecting device.

Put away the alcohol lamp.

Plug the mouth of the test tube with a ball of cotton.

A rubber stopper with a catheter tightens the tube.

Fix the tube containing the medicine.

Heat with an external flame and fix the tube according to the height of the alcohol lamp.

Prevents potassium permanganate from entering the catheter when heated.

4. Heating. Move the alcohol lamp back and forth under the tube.

Heat the area where the drug is located.

Prevent the test tube from bursting due to uneven heating.

5. Collect gas.

The gas collection bottle is filled with water and placed upside down in the sink.

Collect oxygen when there are continuous bubbles at the catheter orifice.

The water is emptied, and the mouth of the bottle is covered with a glass sheet under water.

Remove the gas cylinder and place it on the table.

There must be no air bubbles in the gas collection cylinder. The bubbles that begin to appear at the mouth of the catheter are air that has been heated and expanded. Oxygen is denser than air.

6. Stop the experiment.

Remove the catheter from the water;

Turn off the alcohol lamp.

Reversing the order can cause water to flow back into the tube and cause the tube to rupture.

The reaction device is a solid-solid heating device and the collection device is a drain gas collection device.

1.Potassium permanganate (Mno2) is added to a hydrogen peroxide solution (H2O2) to produce water (H2O) and oxygen (O2).

Potassium permanganate) K2Mno4 (potassium manganate) + Mno2 (manganese dioxide) + O2 (oxygen).

In addition, most of the iron frames built by students are not firm, it is best to check that although the air tightness is checked, but when building, there will still be a lot of rubber stoppers that are not plugged to collect gas, and some students will not hold the gas cylinder with their hands, because they will not pour if they do not hold the bottle at first, but after collecting for a while, the bottle will pour gas and escape.

In the end, it's best to wait until they're done cleaning up and checking that they're all clean before letting them go, otherwise it's all garbage.