Tianyuan Cup chemistry question 09 years, a question of the Tianyuan Cup junior high school chemistr

1) The chemical equation for the reaction in the beaker of scheme B is: 2HCl+CuO==CuCl2+H20. Compared with the two schemes, the obvious disadvantage of scheme A is that excessive CO will cause environmental pollution.

2) If the black copper wire mesh is treated with two schemes A and B, the quality of the copper wire mesh A > the quality of the copper wire mesh B.

Because Cuo in B reacts to form Cu2+ and detach from the copper wire, the mass is lighter.

3) The students in the experimental group found that the liquid in the beaker was corrosive after the reaction according to scheme B and should be treated appropriately. They dispose of the waste liquid by adding iron powder. Add enough iron powder and stir thoroughly, and the final solute in the solution is: FeCl2

The black substance is copper oxide.

After the reaction of carbon monoxide and copper oxide in the first is introduced, a certain amount of copper will be produced, and the mass will be increased by the copper mesh.

After the reaction of copper oxide in B and solution B, copper exists in B as an ionic form and the mass of copper wire mesh B does not increase.

So A is greater than B

The chemical equation in the beaker of scheme 1B is: 2HCl+CuO==CuCl2+H20The obvious disadvantage of scheme A is that excessive CO will cause environmental pollution.

2) If the black copper wire mesh is treated with two schemes A and B, the quality of the copper wire mesh A > the quality of the copper wire mesh B.

Because Cuo in B reacts to form Cu2+ and detach from the copper wire, the mass is lighter.

3) The students in the experimental group found that the liquid in the beaker was corrosive after the reaction according to scheme B and should be treated appropriately. They dispose of the waste liquid by adding iron powder. Add enough iron powder and stir thoroughly, and the final solute in the solution is: FeCl2

Choose B, C.

fe-- h2 si --2h2 al --

a a/28 b b/7 c c/9

Because the mass of the two parts is the same, the mass of hydrogen is also the same.

So a 28 + c 9 = b 7 + c 9

Get a=4c

That is, the mass of iron is 4 times the mass of aluminum.

In the answer, the iron mass in AD is 4 times that of silicon, so BC is chosen

The relative atomic mass of Si is above the multiple-choice questions in the exam paper, if you don't have it, you also have to remember the relative atomic mass of some basic elements.

Suppose the liquid density is 1 g ml

Residual NaOH mass after the first cleaning and dumping: [1g (1g+19g)] * 1g = residual NaOH mass after the second cleaning and dumping: [

Residual NaOH mass after the 3rd wash and pouring: [

And, so choose B.

29 Take 8 grams of an organic compound (the amount of formula is 32), and completely burn it in oxygen to produce 11 grams of carbon dioxide and 9 grams of water, then the organic matter must contain elements, and its chemical formula is . Ingestion of this organic substance can cause poisoning, blindness, and even death, and the chemical name of this organic substance is to write the chemical equation for the combustion of this organic matter in the air.

3. Experimental questions, a total of 18 points.

30 In order to remove a small amount of MgCl2 and MgSo4 in KCl solution, select A, B, and C reagents from Na2SO3 solution, HCL (good filial piety), BA(NO3)2 solution, K2CO3 solution, and BA(OH)2 solution, and follow the following steps

Solution filtrate Purer KCl solution.

Experiments: Experiments, Experiments, Experiments

1) The chemical formulas of the solutes in the three reagents a, b, and c are a, b, and c.

2) In Experiment 1, the addition of solution a should be excessive due to , the relevant chemical equation is and .

3) The purpose of adding excess b in the experiment is , and the relevant chemical equation is .

4) In the experiment, in order to obtain a relatively pure KCl solution, the added reagent C should be appropriate. In this experiment, when the reagent is added, the reagent should be stopped.

31.It is known that the color of copper sulfide (Cus) and cuprous sulfide (Cu2S) powders is similar to that of copper oxide powders and that they are insoluble in water. Calcined in air, both copper sulfide and cuprous sulfide are converted into copper oxide and sulfur dioxide.

According to the above properties, a simple chemical experiment scheme for the identification of copper oxide, copper sulfide and cuprous sulfide powder without any chemical reagents was designed, and the following table was filled.

Experimental Steps, Empirical Phenomena, Conclusions, and Related Chemical Equations.

。The amino group has a certain alkaline interest, and the carboxyl group has a certain acidic interest, so they can be reacted.

You don't need to know the specific principle, it's deeper.

28.Armor. Both silver sulfate and silver chloride are insoluble in water and have no way to separate them by precipitation.

I suggest you memorize the solubility**.

I'm also playing in the semi-finals this year. 3. Question 3 is not good.

28 It must be that the first is not good, silver nitrate can react with sulfate to form slightly soluble silver sulfate (you can check the solubility table), although it is not as good as the precipitation with chloride ions, but there are also some that will affect the judgment, and barium chloride reacts with sulfate to form insoluble nitric acid barium sulfate and does not react with ammonium chloride, so barium chloride should be used.

The third question is to ionize H ions in aqueous solution; NH2 can be combined with H ions in water to separate OH roots, thereby reacting with acids, regardless of the process, and reacting with H in acids. In question 28, while green silver is generated, silver sulfate is also a white precipitate, and it is impossible to distinguish between the two.

Indicates powerless ......

I don't even know what the title is.

It should be available online.

I have, your email address, I'll send it to you.