High school chemistry is mentally handicapped, and high school chemistry is a bit brain dead。。。。。。。

1.Yes, all gases that can be neutralized and absorbed by alkalis are.

2.I haven't used it, I've only seen a grinding gas cylinder with a ground glass sheet, which is not used in real chemical experiments.

3.It is recommended that you still check the meaning of the two nouns, precipitation is an apparent phenomenon, generally a solid is precipitated from a liquid, and a solution is a statement of the degree of dispersion of a substance in another substance, so there is a solid solution. There is no comparison between the two.

4.No, iron hydroxide colloids are prepared under specific experimental conditions, not that iron hydroxide is colloidal. The two terms colloidal and precipitation, like question three, are not conceptual.

4’.The concept of electrolytes.

5.After the iron rod is placed on the anode for a while, it disintegrates due to the loss of electrons, and hydrogen gas is produced in graphite. It is recommended that you look at a concept of cathode and anode.

1.No. 2.You don't need to add when you collect gas, how can you not add it when you save it.

3.Yes, it can only be said that the solubility is very small.

4.Colloids are solutions that dissolve in water particles that meet the requirements of colloids, and the precipitation cannot be called colloids, and when colloids pass through light, they can produce obvious light paths, while solutions cannot.

5. Yes, there is a definition of electrolyte, and the one that can be ionized in the melted or molten state is the electrolyte.

6.The iron rod is placed at the cathode to protect the iron rod, because at the anode, the iron rod loses electrons and becomes ferrous ions, while at the cathode, the electrons are supplied by the power supply, and these electrons can effectively protect the iron rod from oxidation.

That iron hydroxide. There are two types: colloidal and precipitate.

A colloid is a type of molecule with a diameter between a solution and a precipitate.

The iron rod reacts when it is placed on the anode.

Your question is not right, potassium carbonate does not decompose, your temperature is not enough, that temperature is very high, or maybe potassium carbonate is boiling may not decompose, because it is a strong ionic compound.

Then choose D, I don't need to analyze the specifics, just write the chemical formula.

I remember that the carbonates of the active metal do not decompose when heated, and the potassium carbonate should not be converted into potassium oxide and carbon dioxide.

For the original question, just follow the decomposition equation of potassium bicarbonate 2khCO3 ==== k2CO3 + CO2 +H20

The part of the mass that is lost before and after the reaction is water and carbon dioxide, let potassium bicarbonate have xmol, carbon dioxide x 2 mol is generated, water x 2 mol, there is 44 * x 2 + 18 * x 2 = 100 solution x=, so the mass of potassium bicarbonate is, the mass of potassium carbonate is 40g, and the mass fraction seems to be 40%, choose d.

First of all, K2CO3 will not decompose, its decomposition temperature is very high, around 2000 degrees, such a temperature iron glass and the like have long been dissolved, and all this kind of decomposition problem in the future unless it is particularly emphasized that it is decomposed, otherwise K2CO3 Na2CO3 does not decompose.

2khco3==k2co3+h2o+co2 δm100*2 18+44

xx=200*（

Therefore, K2CO3 is 100-60=40 g, i.e. 40% of D

Option d First of all, it is stated that potassium carbonate does not decompose.

Let the original khco3 be x

2khCO3==K2CO3+CO2+H2O due to the reduction in mass are both CO2 and H2O, i.e.

The mass of CO2 and H2O is, 6g, and from the chemical formula, 2kHCO3==K2CO3+CO2+H2O200 62X

x=60, so the mass fraction of K2CO3 is (100-60) 100=40

Potassium bicarbonate is heated and decomposed into potassium carbonate, carbon dioxide and water, but potassium carbonate is heated and does not decompose so that potassium bicarbonate has xmol, resulting in carbon dioxide x 2mol, water x 2mol2khCO3 = K2CO3 + CO2 + H2O44x 2 + 18x 2=

x = the mass of potassium bicarbonate is, the mass of potassium carbonate is 40g, and the mass fraction is 40% d 40

Note: If the water is turned into water vapor under heating conditions and flies away, or if it reacts with potassium oxide to form potassium hydroxide, then potassium hydroxide will also react with carbon dioxide.

Potassium carbonate is very stable, and it will not change much when heated normally. So leave it alone. I don't have scratch paper on hand, you can figure it out yourself.

Potassium bicarbonate produces potassium carbonate, carbon dioxide and water, and it is good to count the poor quality of potassium bicarbonate and potassium carbonate.