In junior high school chemistry, there must be a problem solving process, and it is best to explain

The first floor is right, but I don't know if you can understand it? I'll use the more troublesome algorithm to calculate!

fe2o3+3co=2fe+3co2

Because it is only heated for a period of time, there will still be Fe2O3 leftover, so the remaining solid mass is: the remaining Fe2O3 + Fe generated

It will be: all Fe2O3 - the remaining Fe2O3 - the generated Fe. It would be: Fe2O3 participating in the reaction - Fe= generated.

Let the mass of the generated Fe be X. then x 112=,x=hope!! Let's go into detail!!

Fe2O3 + 3Co = High temperature = 2Fe + 3CO2 Solid mass decreases.

x112/x=48

x = the mass of iron produced by the reaction is.

Fe2O3 + 3Co = 2Fe + 3CO2 residual solid is a mixture of Fe and Fe2O3, the original solid is 12g, indicating that a part of O has run away.

Conservation according to atomic mass.

The reduction is all the O atoms in Fe2O3, and 3 O atoms correspond to 1 Fe2O3112 m=48

m== is all the mass of Fe after reduction.

fe= g if it helps you, xiexie

According to the title. Fe2O3 + 3Co = High temperature = 2Fe + 3Co2 Because a part of the reaction Fe2O3 becomes Fe, the solid mass decreases.

x is the mass of the oxygen element.

112/x=48

x = the mass of iron produced by the reaction is.

Analysis: From Fe2O3 to Fe, what is reduced is oxygen:

fe2o3→2fe △m

m112：m=

So m=

The chemical formula of G is H2, and the basic type of chemical reaction between E and F is: chemical reaction, write one of the uses of substance B: fire extinguishing agent.

2) The chemical equation for the reaction of c and d may be; 3CO + Fe2O3 = High temperature = 2Fe + 3CO2

Analysis: A is the acid contained in the human gastric juice, then it must be hydrochloric acid, G is the lightest gas, then it must be hydrogen, and B, C, D, E, F are all oxides, the oxides that can react with acid must be metal oxides, then D, E must be metal oxides, G and F can be converted into each other, F must be water, F is water, then the metal oxides that can react with water are only calcium oxide, and E is calcium oxide. D may be copper oxide or iron oxide, etc., the oxide that can react with metal oxide must be reducing, then C must be carbon monoxide, then B is carbon dioxide.

Because carbon monoxide and carbon dioxide can be converted into each other.

What is the problem?

a:hclf:h2o

G: H2 You gave me the title completely, thank you!

H2, chemical reaction, fire extinguishing the same as below.

In the inference problem, acid is usually the key to solving the problem, followed by salt, pay attention to the reaction of various metal oxides and acids, especially copper oxide, Cuo can react with acid, and there are various colored substances, such as soluble copper salt, the aqueous solution is blue, the soluble ferrous salt is light green, the soluble iron salt is light yellow, the copper precipitate such as Cu(OH)2 is blue, this is to remove the copper precipitation, the precipitation of iron salt, such as Fe(OH)3, is reddish-brown precipitation, and there are several precipitations to pay special attention to, only two are silver chloride and barium sulfate.

The experimental questions grasp the purpose of the experiment, control the variables, and then solve them one by one.

Focus on solving the second question of the block solid should be placed in place (fill in "a" or "b"), why is the answer b, I asked the teacher what he said to stop reacting, I don't understand.

Answer: This is a simple Qipu generator type device. After the piston is opened, the liquid drug in the long-neck funnel will enter the large test tube, and when it comes into contact with the solid, it reacts to produce gas; Close the piston, because the drug continues to react to produce gas, the gas pressure in the large test tube increases, so that the liquid drug is pressed back into the long-neck funnel, the solid and liquid are separated, and the reaction is stopped.

Repeating the opening and closing of the piston allows the reaction to occur freely. Therefore, the solid should be placed on top of the perforated plastic plate at point A. If placed at B, the reaction will continue after the piston is closed, causing the gas to run out of the long neck funnel or causing the liquid in the long neck funnel to spill out of the long neck funnel because the device is not able to let all the liquid into the long neck funnel, which is prone to danger.

This is also the reason why you need to add a perforated plastic plate, if you can put it at B, there is no need to put the perforated plastic plate.

Because gas is generated, when the gas hides to a certain extent, the liquid will be pressed back and the reaction will stop.

How to answer the picture if it is not uploaded Question 4 Cu+H2SO4 (dilute) + H2O2=== ===CuSO4+2H2O hydrogen peroxide acts as a strong oxidant.

I can't see the picture, just look at the title, there are three possibilities for precipitation here, barium carbonate or barium sulfate, and magnesium hydroxide.

1. If the precipitation is not produced immediately, then there must be hydrochloric acid, no sulfuric acid, no sodium carbonate, and the precipitation is magnesium hydroxide.

2. If the precipitate is produced immediately and it is a straight line, it may be a solution of Na2CO3 and MgCl2, which does not contain acid.

It may also be sulfuric acid, hydrochloric acid solution, without mgCl2, Na2CO3

3. If the precipitation is immediately generated, and it is a broken line, it may be sulfuric acid and MgCl2 solution, and hydrochloric acid cannot be determined.

Sodium chloride does not need to be considered, it is dispensable, so D must be wrong. The rest you look at and look at ...

1. Analysis: Because the chemical formula of potassium peroxide is K2O2 and the chemical formula of potassium superoxide is K2O4, the ratio of the number of potassium atoms to oxygen atoms is 2:3 (the mass ratio is 2 39:3 16) according to the potassium content

Therefore, the ratio of the number of peroxide ions to superoxide ions is 1:1 (so that the ratio of potassium atoms to oxygen atoms is 4:6).

2 3 = 18 species.

3. The prototypes of C4 and D substances are as follows: AlCl3 Alf3 SO3 NF3 NH3 BCL3

Question 2 Answer: Two 1H are combined with 16O, 17O, and 18O, and two 2H are combined with three oxygen atoms.

There are three combinations of two 3h and three oxygen atoms respectively, a total of 9 kinds.

In addition, one 1h and 2h are in three combinations of three oxygen atoms, and one 1h and 3h are ...... respectivelyThere are three kinds.

A 2h and 3h ...... respectivelyThere are three and nine kinds, so there are 18 in total.

Question 4 Answer: Treat h as a halogen element, which is negative and can be combined with the positive trivalent of the third and fifth main groups, and xy can also be positive hexavalent and y is negative bivalent, such as SO3

1: It can be easily found by the cross method: ko2: 39 71 78 126-39 87

ko2:39/71 39/71-78/126

The ratio is: (78 126-39 87):(39 71-78 126)2:H2 has 6 species, and O has 3 species, so there are 18 species in total.

3：c，h2》o2

4；D BCL3, M = 12, excluding AC, NH3, M-4, excluding B

The gas mixture passes through a sufficient amount of hot copper oxide, that is to say, all the CO in it is converted into the mass of the carbon element of the gas mixture: 5gx36%=. There are the following variations in this question:

C--CO2---CaCO3, all C's are converted to CO2, all CO2 is converted to CaCO3, and the mass of CaCO3 can be obtained from the mass of carbon by the relation C--CO2---CaCO3. Let the mass of the white precipitate be x

c--co2---caco3

12 100x

x=15g

First of all, according to the title, to know what reaction is happening, 5g of gas is calcine copper oxide by a sufficient amount, that is to say, all the CO in it is converted into CO2 equation co+cuo==CO2+cu

The gas that came out was all carbon dioxide.

Then I put a sufficient amount of gas into the clarified lime water, and the precipitate must be caCO3, and I asked, "You Moores have learned how to cut this thing."