I can t understand a small step in the answer to a high school chemistry question, I hope to answer,

The solution is electrically neutral, so the total number of positive and negative charges is equal, that is, [H+] 2[Fe2+] 3[Fe3+] = 2[SO42-], which represents the amount concentration of the substance, and the element has n charge before multiplying N), let the concentration of each cation be x, because the concentration of each cation is equal, so x + 2x + 3x = 2 * 6, so x = 2 mol l, so n(H2SO4) = 2 * 2 = ,n(feSO4)=2 * = ,n[fe2( SO4)3]=2*2 = Because H2SO4 dissolves iron, Fe2(SO4)3 can undergo redox reaction with iron to form Fe2+, so theoretically the maximum mass of dissolved iron powder is: 56*=

As for the answer, because the cation concentration is equal, the concentration of H+, Fe2+ and Fe3+ is equal, so the ratio of the amount of the three solutes is 1:2:1, but the concentration ratio of sulfuric acid, ferrous sulfate, and ferric sulfate is not 2:

2:3, but 1:2:

1, it should be to remove the cation metering number in the compound, but the answer is to multiply the cation metering number in the compound to get 7, so the answer is wrong.

You won the lottery lol and the answer was wrong.

The contradiction is obvious.

Since the ratio of the quantities of the three solutes is 1:2:1

So:::2:1???

Correct H2SO4

feso4fe2(so4)3

[Idea]: After putting iron powder into the mixed solution of Fe2(SO4)3 and CuSO4, Fe3+ and Cu2+ can react with iron, but due to oxidizing Fe3+ >Cu2+, Fe should be reduced to Fe3+ first, that is, the reaction occurs first: Fe + 2Fe3 + = 3Fe2+, but this reaction cannot only occur for two reasons:

The first is that if only this reaction occurs, it means that there is less iron powder, and there is no residue left in the complete reaction, so there can be no insoluble matter; Second, if only this reaction occurs, the FeSO4 generated can be calculated according to this reaction as (6g 56g mol) 3=> through the above analysis, it can be seen that after reducing all Fe3+, the reaction of reducing Cu2+ does not occur, and whether there is any residual Fe at this time That is, there must be Cu in the remaining solid, whether it contains Fe This is the key to this problem, which needs to be determined by calculation and derivation.

Analysis]: The chemical equation for the reaction to occur is:

fe+fe2(so4)3=3feso4 ②fe+cuso4=cu+feso4

The two reactions co-generate FeSo4.

fe ～ feso4

1mol 1mol

aa=, that is, iron, then the solid contains Cu and the remaining Fe, and the amounts of Fe2(SO4)3 and CuSO4 of the original solution are x and y., respectively

fe+fe2(so4)3=3feso4 fe+cuso4=cu+feso4

x x 3x y y y y

3x+y=

6g-56g/mol×(x+y)+64g/mol×y=

Solution: x= y=

then copper is generated. The amount concentration of the original Fe2(SO4)3 and the substance is.

fe2(so4)3+fe=3feso4

x 3xcuso4+ fe= feso4+cu

y y y3x+y= 6-(x+y)56+64y=x= y=

Copper is formed after the reaction.

The amount of Fe2(SO4)3 substance x =

The amount concentration of Fe2(SO4)3 substance is:

Cellulose (C6H10O5)n, in high school, there is only cellulose and starch, and he says that it is made from bagasse, so it is only cellulose, and starch is generally found in pasta, in fiber vegetarian plants.

Glucose, the substance that reacts with silver ammonia, must have an aldehyde group that binds to the cellulose on it, and then there is only glucose, and the rest of the monosaccharides have no aldehyde group.

The carboxyl group is not actually a carboxyl group, it should be like this, r-coonh4.

Light energy, chemical energy, this is photosynthesis, needless to say...

C2H5OH + CH3COOH---C2H5OOCCH3 + H2O esterification reaction If there is concentrated sulfuric acid, you generally have to think of this first, and when esterification reaction, acid dehydroxyl alcohol dehydrogenation.

2C2H5OH+O2-2CH3CHO+2H2O This is a typical oxidation reaction, oxidizing the aldehyde group with hydroxyl group, if you want to reduce the aldehyde group to the hydroxyl group, it is hydrogenation, and the general oxidation has R-C-OH to R-CHO and then to R-Cooh

1. Cellulose, glucose, alcohol, hydroxyl group, carboxyl group.

2. Light energy Chemical energy.

Esterification of 3C2H5OH+CH3CoOH-C2H5OOCCH3+H2O.

4 2c2h5oh+o2-2ch3cho+2h2o

Choose B, this question looks at the amount of Y substance, a Y2O3 has 2 Y, as long as Y2O3, it also needs mol of BaCO3 and mol of Cuo. If you do this kind of problem, you will have no problem at all according to the conservation of mass.

b Conservation of Elements The compound has atoms 1mol barium copper then Y2O3 requires BaCO3 1

Choose b, no need to calculate, this question can be selected according to the molar amount of y, a y2o3 has 2 y, as long as.

Pick B, it's so easy! Conservation!