Ask for help with a few junior high school chemistry questions!

All written by myself, correct answer:

1.For a long time, scientists believed that noble gases do not react chemically with any substance, and called noble gases "noble gases", which has constrained the study of the chemical properties of noble gases for a long time. In fact, noble gases can react with other substances to form some noble gas compounds, which are not required to be mastered in middle school.

2.The method is to put the burning sticks into the mouth of the gas collection cylinder containing the three gases, and the sticks burn more violently in the oxygen, but continue to burn in the air, and extinguish the sticks in the nitrogen. In this case, nitrogen is often replaced with carbon dioxide.

It is important to remember not to use spark-bearing sticks to identify these three gases, because spark-bearing sticks will soon be extinguished in the air, so it is not easy to distinguish between air and nitrogen.

3.Oxygen is an oxidant, you can understand it as an accelerant in junior high school, and combustibles are oxidized and exothermic by oxygen to cause combustion, so oxygen cannot be used as fuel, yes"Substances that support the combustion of combustibles"。

The general knowledge of geography about environmental protection is mentioned in chemistry textbooks.

5.Because the temperature of the flame is different at different positions, the outer flame is higher than the inner flame and higher than the flame center, so the result is that the test tube bursts due to uneven heating. The correct way is to move the test tube back and forth on the outer flame of the flame to heat it evenly, and then use the external flame of the alcohol lamp to concentrate the heating at the position that needs to be heated.

6.The reason why carbon dioxide makes the clarified lime water turbid is that the carbon dioxide reacts with the solute calcium hydroxide of the lime water to generate water and calcium carbonate precipitation, the calcium carbonate precipitates are white, and the precipitation is suspended in water, which is manifested as the clarified lime water becomes turbid, and the reaction equation is Ca(OH)2+CO2=CaCO3(precipitation)+H2O, because the precipitation is white, it is said that a white solid is generated, and the suspended white solid is the reason why the lime water becomes turbid, that is, the white solid and turbidity are essentially the same.

I'm so tired, I hope it can help you

1.Xenon can react with fluorine to form xenon tetrafluoride (special case) XEF42The wood strips are more vigorous for oxygen, unchanged for air, and extinguished for nitrogen. (Oxygen fuels the flame more vigorously, nitrogen does not support combustion).

3.Oxygen is a combustible and cannot be used as fuel.

The reasons are slightly ......）

5.Explosion (uneven heating, different temperature of internal and external flames, high outside and low inside) 6The reason for the turbidity is the production of calcium carbonate, which adheres to the wall and bottom of the bottle. Open! The turbidity occurs because the solution is not standing, and the calcium carbonate particles are suspended in the water.

1.Xenon and fluorine can react with XEF6

And PTF6

2.The burning wooden strips are put into three glass bottles containing the same volume of gas in turn, and the nitrogen gas cannot make the wooden strips continue to burn, and the air and oxygen can support the continuous burning of the wooden strips, but the combustion time of the equal volume of air is shorter than that of the same volume of oxygen, because there is not only oxygen but also CO2 in the air, so the three gases can be identified.

3.Oxygen is only an accelerant, not a fuel, it can only support combustion, and it cannot spontaneously combust itself.

The test tube will rupture because the alcohol wick is an internal flame and its temperature is very high.

6.The white substance is calcium carbonate because calcium hydroxide reacts with carbon dioxide to form a white calcium carbonate caCO3 precipitate.

I don't understand hi me o( o

1.Xenon and fluorine can react under certain conditions to form xenon tetrafluoride.

This question is very out-of-the-box! ）

2.Stick a burning wooden strip into each of the three gases.

Burns more vigorously - oxygen.

The combustion situation remains the same - air.

Burning sticks extinguish – nitrogen.

3.No. Oxygen is flammable, but not flammable. So oxygen can be used as an accelerant, but not not.

as fuel. Because vegetation has the effect of fixing sand and blocking sand.

This question is obviously a biology and geography question! ）

5.The test tube bursts due to uneven heating.

6.Calcium carbonate. Carbon dioxide + calcium hydroxide = calcium carbonate.

Please don't copy and paste! Plagiarism is shameful! Original !! by Michael Young

1.I don't know if I don't learn rare gases in the third year of junior high school.

2.Put the burning wooden strip into a gas collection cylinder with three kinds of gases, and the wooden strip in the air can burn for a while; The sticks of wood in the oxygen will burn more violently; The nitrogen will be extinguished immediately. (There is some oxygen in the air; Oxygen is pure oxygen; Oxygen-fueled; Nitrogen does not support combustion).

3.No. (Oxygen fuels but does not burn).

Plants have the role of fixing the soil and can maintain soil and water).

5.The test tube ruptures. (The alcohol lamp core has the highest temperature, which is easy to rupture the test tube.)

6.Because of the white solid material that appears on the wall and bottom of the bottle, the lime water becomes cloudy. The white solid is calcium carbonate.

CO2 + Ca(OH)2 = CaCO2 + H2O, that is, carbon dioxide plus calcium hydroxide (lime water) is equal to calcium carbonate (CaCO2) plus water (H2O).

1.Xenon and fluorine can react under certain conditions to form xenon tetrafluoride.

2.It is unchanged in the air, extinguished in nitrogen, and more vigorous in oxygen.

3.No, it is not flammable, it is combustible.

Trees can block wind and sand.

5.The temperature of the inner flame is not as high as that of the outer flame, resulting in uneven heating and bursting of the test tube.

6.Calcium carbonate is insoluble and a white solid.

1: Chlorine. 2: No change in air, re-ignition in oxygen, extinguishment in nitrogen.

3: Yes. 4：a

5: The alcohol lamp is turned off.

6: Precipitated calcium carbonate.

1 b is not wrong.

Ammonium chloride chemical formula NH4Cl, formula amount.

Ammonium;Chemical formula: NH4+) is a positive ion derived from an ammonia molecule. Ammonia molecules combine with a hydrogen ion to form ammonium ions (ammonia donating lone pairs). Because its chemical properties are similar to metal ions, it is named "ammonium".

So, there's nothing wrong with B.

2 Note that it is a sodium carbonate solution, and Na2O reacts with water: Na2O H2O 2NaO

So the correct answer is: Na2CO3 + CAoO H2O=CaCO3 precipitate + 2NaOH

1.False, the precipitate is mostly insoluble (less than grams per 100 grams of water dissolved at 20 °C), that is, there is no absolutely insoluble matter, and the precipitate is only a small part of the dissolution.

2.Wrong, when the microsoluble matter is used as a reactant, it is considered soluble and can react with other substances, such as calcium hydroxide and sodium carbonate. Just give a counterexample to overturn it