Grade 9 Chemical Oxygen Knowledge Tree Rush 5

In the ninth grade, you only need to know the reaction formula, phenomenon and product of oxygen and carbon, the reaction phenomenon and formula of oxygen and iron (ferric oxide), the reaction formula, phenomenon and product of oxygen and sulfur, and the phenomenon and product of hydrogen. Let's study after high school.

If you want to produce oxygen, you still have to know the nature of foreign gas.

Properties of OxygenPhysical Properties of Oxygen Under normal conditions, oxygen is a colorless, odorless gas that is not easily soluble in water. Under standard conditions, oxygen is slightly denser than air, and at a pressure of 101 kPa, oxygen becomes a light blue liquid at -183 and a light blue snowflake at -218.

Usage of light, flame, fog, and smoke Light: Solid matter glows when burned, such as iron bars emitting dazzling bright light when burned in the air. Flame:

The combustion of gaseous substances produces flames, such as hydrogen burning in the air to produce a light blue flame (some solids, such as paraffin wax combustion produce flames, which are actually vaporized vapors combusting). Fog:

Big. <> Uses of Oxygen The nature of oxygen determines the use of oxygen. An important use of oxygen is to supply respiration and support combustion. Oxygen can also be used for gas welding, gas cutting, liquid oxygen explosives, rocket propellants, etc.

Manganese dioxide is used as a catalyst and does not participate in the reaction.

After potassium permanganate is heated to produce oxygen, it is still solid and remains in the test tube.

Eventually, the oxygen is denser than air and is collected into the gas collection cylinder through the slightly downward inclined tube and the tube at the mouth of the tube.

The matters to be noted are: 1. Check the air tightness of the device before reacting.

2. Preheat before heating to prevent test tubes**.

3. During the experiment, the mouth of the test tube should be slightly inclined downward to prevent the water on the potassium permanganate from accumulating at the bottom of the test tube.

4. The mouth of the test tube should be padded with a layer of cotton to make the oxygen obtained more pure.

5. If the drainage method is used to collect oxygen, the gas collector cylinder and conduit should be taken out of the water surface before extinguishing the alcohol lamp to prevent the water from flowing backwards.

The experiment you did was probably a small amount.

Of course, the gas collector cylinder is oxygen, and it is gas, and potassium manganate and manganese dioxide are all in the test tube

1. Decompose hydrogen peroxide to produce oxygen.

1) Catalyst: A substance that can change the reaction rate of other substances in a chemical reaction, but its mass and chemical properties do not change before and after the reaction is called a catalyst (also known as a catalyst).

2) Features: "one change and two unchanged".

One change: change the rate of chemical reaction (faster or slower).

2. Unchanged: its own mass and chemical properties remain unchanged.

3) Reaction principle: hydrogen peroxide (add) manganese dioxide - water + oxygen.

2. Heating potassium chlorate to produce oxygen.

1) Reaction principle: potassium chlorate - (add) manganese dioxide (and heat) - potassium chloride + oxygen (manganese dioxide on top, heating on bottom).

3. Heating potassium permanganate to produce oxygen.

1) Reaction principle: potassium permanganate - (heating) - potassium manganate + manganese dioxide + oxygen.

Fourth, decomposition reaction.

1) is the basic type of reaction.

2) Meaning: The reaction of two or more other substances from the reaction of one substance is called a decomposition reaction.

3) Features: "one" becomes "many".

5. Heating potassium permanganate to produce oxygen.

1. Experimental supplies: iron frame, sink, gas collection bottle, alcohol lamp, test tube, rubber stopper with catheter, potassium permanganate.

2. Steps.

1) Check: Check the airtightness of the device.

2) Packing: Loading medicines.

3) Fixed: Fix the test tube.

4) Point: Light the alcohol lamp.

5) Harvesting: Collecting oxygen (using the drainage method).

6) Detachment: Evacuate the catheter from the sink.

7) Off: Extinguish the alcohol lamp.

3. Precautions.

1) Be sure to check the airtightness of the device.

2) When fixing the test tube, the mouth of the test tube should be slightly inclined downward. [Prevent condensate from backflowing and bursting the test tube].

3) When heating, it should be preheated first and then heated centrally.

4) The catheter in the test tube is just exposed to the rubber stopper. [Easy to vent gas].

5) When the gas is collected by the drainage method, the air bubbles just generated at the catheter mouth cannot be collected immediately. [The bubbles produced at this point are the air expelled from the test tubes and catheters.] If collected, the collected gas (oxygen) is not pure].

6) When heating potassium permanganate to produce oxygen, a ball of cotton should be plugged at the mouth of the test tube [to prevent the powder of potassium permanganate from entering the conduit during heating and turning the water in the sink red].

7) After the experiment, remove the catheter from the sink and then extinguish the alcohol lamp. [Prevent the water in the sink from flowing backwards and bursting the test tube].

Here are my chemistry notes, I hope it helps you. It is best to read the notes and the diagram of the experimental setup while reading the book.

Basic knowledge and theory: 8. Composition of air: nitrogen 88%, oxygen 88%, rare gases, carbon dioxide, other gases such as:

Each oxygen molecule is composed of 8 oxygen atoms, so the chemical formula of oxygen is O8 Diatomic molecule elemental chemical formula: O8 (oxygen), N8 (nitrogen.