A kind of chemistry problem, please talk about the detailed idea

This requires you to be familiar with the valence state of this element. For example, sulfur has several valence states, such as -2, +4, and +6, and the higher valence state has oxidation, and the lower valence state has reduction. The intermediate valence state has both oxidation and reduction, depending on the specific reaction.

In addition, the most ** state of an element only oxidizes (there is no reduction, because it can no longer be oxidized and rises), on the contrary, the lowest price is only reduction.

I believe you should be in high school, there is a valence list in the junior high school chemistry book, you can review it, find some information to see.

In addition, do more questions, you can know a lot of information from the questions. For example, if you mention chlorine dioxide as a substance that can be used for disinfection, then you will find out that chlorine has a valence of +4. That's probably it, come on

Each element has many valence states.

Relying on low prices is reductive, ** is oxidizing.

Like Cl, 1-valent is reductive and positive 7-valent is oxidizing.

Redox is judged on the basis of the specific reaction, because the elements in the intermediate valence state of many compounds may be both oxidizing and reducing. Some elements even act as both oxidizing and reducing agents in the same reaction. There are more such elements.

You can look up the reaction between manganese (MN) and nitrogen.

Generally, ** elements are oxidizing, and low-cost elements are reducing, which depends on daily accumulation. After a few years, if you are given a substance, you will be able to associate its associated chemical reactions, and then judge its oxidation.

Summary. Students should pay attention to the process of experiment: pay attention to the reaction of phenolic hydroxyl group with sodium hydroxide first to prevent the phenolic hydroxyl group from being oxidized, and finally react with hydrochloric acid to obtain the target product.

How to do this chemistry problem, ask for a quick answer.

** Reversed. Shoot right.

The first 5 questions of this question.

You don't need to go into details.

1) A is C6H6

The name is Aromatic Trail.

2) B is CH3

3), for the substitution reaction.

4) The type of reaction replaces the reaction.

5)) Phenolic hydroxyl group.

Hello students, this question examines the synthesis of organic matter, involving the naming of organic matter, the identification of functional groups, the type of organic reaction, the writing of organic reaction equations, the writing of restriction isomers, the design of synthetic routes, etc.

It should be noted in the process of the same pin bending experiment: it should be noted that the phenolic hydroxyl group should first react with sodium hydroxide to prevent the phenolic hydroxyl group from being oxidized, and finally react with hydrochloric acid to obtain the target product.

If you have any questions you don't understand, or if you have any difficulties with your homework, you can always consult me.

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Suppose the precipitated crystal mass is xg, which you think (meaning the reduced mass of the solution.

Knowing that the solubility of CuSO4 at 20 is 16g, what is the precipitated crystal mass?

cuso4+5h2o=

16g a=25g

The water of the reaction precipitates crystals.

The quality of the precipitated crystals is.

If anhydrous CuSO4 is put in, the Saturated solution of CuSO4 is exactly all converted into crystals, and what is the mass of the saturated solution.

The solubility of CuSO4 is known to be 16g at 20

cuso4+5h2o=

The saturated solution mass is.

Select C, after putting it in, it will absorb the water in the solution and become copper sulfate crystals, while the original saturated solution will precipitate some crystals because it loses water, so the total crystal amount will be greater.

Anhydrous copper sulphate absorbs water because the chemical formula of the crystal is CuSO4·5H2O and according to the definition of solubility, it is: x=

The saturated solution mass is.

[Analysis].

The corresponding method of a typical binary mixture is a system of binary equations, and the calculation is very simple if the unknown is the quantity of matter.

First calculate the reaction with hydrochloric acid.

The amount of OH- is expanded by a factor of 10 to be the total amount of matter of the original mixture, and then the sum of the masses and the sum of the quantities of the matter are a series of equations.

Solution] n(hcl)=

original mixture.

n(oh-)=

Let the quantities of substances of naoh and koh be respectively.

xmol，ymol

x＋y＝0．0525

40x ＋56y ＝2．5

x ＝0．0275

y＝0．025

m（naoh）＝40g／mol＊0．0275mol＝1．1gm（koh）＝0．025mol＊56g／mol＝1．4g

Let the masses be xy

The amount of substances for each substance OH can be found.

The total amount of substances from hydrochloric acid to which OH is introduced.

and xy and for.

A system of equations emerges simultaneously.

Just solve the system of equations.

According to the chemical formula, this compound is a halogenated hydrocarbon containing a carbon-carbon double bond, which is equivalent to the product of replacing one hydrogen atom in propylene with a chlorine atom, so there are three types in total. And because there is cis-trans isomerism in 1 chlorine and 1 propylene, there are 4 kinds in total, and the answer is b.

Because the relative atomic mass Na=23, K=39, Zn=652Na+2HCl===2NaCl+H2

2k+2hcl===2kcl+h2

zn+2hcl===zncl2+h2

That is to say, 1mol of sodium or potassium reacts with 1mol of hydrochloric acid to produce 1mol of hydrochloric acid.

And 1mol of zinc and 1mol of hydrochloric acid react to form 2mol of hydrogen]

If the mass of all three metals is 3 grams, there is an excess of hydrochloric acid, then.

The amount of hydrogen produced by reaction with sodium n hydrogen = (3 23) 2 The amount of hydrogen produced by reaction with potassium n Hydrogen = (Yunshou 3 39) 2 The amount of hydrogen produced by reaction with zinc n Hydrogen = 3 65

The amount of hydrogen producedna>zn>k】

If the mass of all three metals is 3 grams, and the zinc and potassium reactions are complete, there is a residual side suspicion of sodium.

The amount of hydrogen produced na>k=zn].

It's all equal mass, find out their molar number, and then according to sodium and potassium is monovalent, so divide by 2, zinc is bivalent, and get the size.

First, find the mass fraction p of n in NH4NO3

Then find the mass fraction q of n in Co(NH2)2

Let the mass fraction of NH4NO3 in the mixture be x

Then the mass fraction of Co(NH2)2 in the mixture is 1-x, which is obtained from the problem Xp+(1-x)*q=40%.

x can be found

The idea is:

Assuming that ammonium nitrate has xg and urea has yg, the mass of n elements in the mixture can be calculated, and the mass fraction of n elements can be listed by the equation about xy. It has x,y on its numerator and denominator. But don't be afraid, you just have to simplify it and end up with an equation of x=ny.

Then you calculate x (x+y), which can be easily broken.

One point of view, don't be intimidated by two unknowns.