Chemistry topics. Masters, please come in! Chemistry questions, master advances!

First of all, SO42 is selected as the first group, so that AG+, BA2+ will definitely not be the first group, and will produce precipitation, and by analogy CL, OH will definitely not be the second group, because there is AG+, Fe3+ must be the second group because there is OH, because of the electric neutrality, the second group must have NO3 anion, and the first group must have Na+

Therefore, the first group is SO42, Na+, Cl, OH A (pH>7).

The second group is ag+, fe3+, ba2+, no3 b.

1. A basic so there is oh-

Therefore A cannot have iron and silver.

2, so B has iron and silver, so B does not have sulfate and cl- (because silver sulfide is insoluble and silver acid is slightly soluble), then the two anions will be in A.

3. A must have cations, and there can be no barium (barium sulfate is insoluble), and the four types of A have been determined: Oh- (SO4)2-Cl- Na+, corresponding to B AG+ Fe3+ NO3- BA2+

The sewage discharged from workshop A has a pH value of 7 and is alkaline.

The present ions are: Na+, (SO4)2-, NO3-, OH-

The rest is from workshop B. ba2+，cl－，fe3+、ag+。

Investigate the problem of ion coexistence.

Plant A's pH 7 is indicated to be alkaline, and it is obvious that only Na+ can be among the eight ions mentioned in the questionso42- cl- no3-

A: OH, Cl, SO42, Na+

B: AG+, Fe3+, BA2+, NO3-

Analysis: A pH value is 7, so there must be a basic ion OH-, because AG+, Fe3+ does not coexist with it, in B. In the same way, SO42 and AG+ do not coexist in A, and in the same way, Ba2+ must be in B.

Finally, through the conservation of electric charge, A needs cations and B needs anions, and the answer is obtained.

Because the pH of the first is greater than seven, it contains OH, and there should be no precipitation and microsoluble. There can be no BA ag FeTo comply with the principle of electric neutrality, there must be na

Because there are four kinds of anion and ion, respectively).So B contains ag ba feIf there is no precipitation, it contains NO3

A also contains SO2 clThis type of question focuses on the use of the principles of electrical neutrality and non-precipitation.

Analyze the valency of the s. In the reaction, the valency of S is 0, and after the reaction, S in K2SO3 is +4 valence, and S in 2K2S is -2, so the valency of 1 S atom is increased and oxidized, and the valency of 2 atoms is reduced and reduced. So:

The ratio of the number of atoms that are oxidized to those that are reduced is 1:2

There is red phosphorus on the match head: the outermost shell of phosphorus has five electrons, so there are five valence states. Therefore, P2O5 can be obtained

po2p2o3

POP2O five substances.

Then there is also the element of carbon in the match, the element hydrogen and oxygen, which is burned to produce carbon dioxide, carbon monoxide and a small amount of water.

Experimental phenomenon of the reaction of copper sulfate and sodium hydroxide after mixing.

A blue precipitate Cu(OH)2 is generated

AL: That's wrong, the law of conservation of mass is generally for chemical reactions, and the decrease in mass after water heating for a period of time is a physical change process.

b, as we know from the equation, 3GC reacts with 8go2 to form 11gCO2, and 1GC will react with CO2 again, so it is impossible to generate 12gCO2

c.Anyway, it must be wrong to say that the mass is not conserved, and the increase in the mass of iron in humid air is due to the rusting of Fe, and a chemical reaction occurs to generate Fe3O4

D is right, because the reaction produces gas, so the mass becomes lighter Zn+CuSO4==Cu+ZNSO4, and the displacement reaction, Zn is more active than Cu.

Copper hydroxide blue precipitate is generated.

Option B, the law of conservation of mass is a law that must exist.

The quality does not change before and after.

zn+cuso4=znso4+cu

The increased mass of the cathode is the metal formed by the reduction of metal ions in the electrolyte solution, and the amount of precipitated metal can be compared under the same electric condition.

Suppose the amount of electricity is 2mol,a

Precipitate zinc 1mol

b precipitates 2mol of silver

c. Precipitate 1mol of copper

d. Precipitate potassium 2mol

Compare their mass ag precipitates the most, so choose B

Option D analysis: metal and non-metal compounding can generate salts; Basic oxides and acids react to form salts; The reaction of alkali and acid can produce salts; Acidic oxides and bases react to form salts.

A is SiO2 (silicon dioxide.

b is CO2 (carbon dioxide.

C is Na2SiO3 (sodium silicate.

D is H2SiO3 (silicate colloid.

Let's check the book for yourself about the reaction.

If you think about it, it's all equations in the book....a:sio2

Formation of new matter Combustion, heat release, and the formation of new matter.

Physical melting, mass becoming smaller, density changing.

Chemical properties: The properties of a substance in the process of chemical change.

Physical Properties: Properties of matter that exhibit without a chemical reaction CO Physical Properties: Gas.

Chemical properties are: flammability, toxicity.

Chemical change: CO+02 CO2

1A magnesium chloride and sodium chloride (table salt) are two substances though.

But they are all soluble in water.

bCarbon dioxide is introduced into lime water.

Calcium carbonate is generated.

Calcium carbonate is insoluble in water.

CO2 + Ca(OH)2==CaCO3 + H2OC are elemental.

d is formed by the reaction of water with calcium oxide.

Not a solution. cao+h2o=ca(oh)2

Therefore, A2A is selected to form an emulsion.

b suspension. c. Copper sulfate cannot be stirred.

dAlcohol is miscible with water.

Therefore, the choice of d gallium is anhydrous copper sulfate.

The solution is prepared with bile alum.

3. The copper sulfate solution is blue.

Copper sulphate is toxic.

1:DA is a mixture of MgCl2 and NaCl.

b is because of a small amount of CO2

So the reaction is ca

oh)2 will not run out of reactions.

CaCO3 and CA are generated

OH)2 mixture.

cIt is a substance.

H2OD is CA

OH)2 solution.

2: CDAB is considered organic and not miscible with water.

What does bile alum mean: It is the crystalline water form of copper sulphate.

He and copper sulphate are completely soluble in water and are a solution.

This question should be about cuso4

3:C alum refers to KAL(SO4)2·12H2O that can be used to purify water quality.

However, due to the excessive accumulation of Al3+, it is harmful to the human body.

It is not recommended at this time.

Table salt is NACL

It will not be blue.

Hydrated lime is cao

When it is put into water, Ca(OH)2 is generated

It won't be blue either.

Cu2+ in copper sulphate is blue in color.

Meet the requirements. Because copper ions are heavy metals.

Harmful to the human body.

It's toxic

1、ad

CO2 is passed into the clarified lime water.

CaCO3 precipitation is present.

Ice water mixture.

The medium ice is solid, and if there are no impurities, the ice-water mixture is pure, and the solution is mixture 2, cd

Oil and water are not tolerated, and eventually stratification.

Flour is a macromolecular organic matter, the same as above.

Copper sulfate is soluble in water, and alcohol is miscible with water in any proportion.

Cholelum is CuSO4·5H2O, which is a blue crystal.

Copper sulphate is CuSO4

Anhydrous copper sulphate.

Cuso4 is a white solid.

3. C copper sulfate is toxic.

A, C, and D can be sterilized, but only C is blue, but it is generally disinfected with hypochlorous acid. . .

6no2+8nh3=7n2+12h2o

6no+4nh3=5n2+6h2o

n(no2)+n(n0)=3l/

n(nh3)= /

Let n(no2)=x

By then n(n0)=(

Again, by chemical equations.

Connected and easy to obtain.

x/6*8+(

Just solve it. If you don't understand, ask again, thank you.

6no+4nh3 = 5n2+6h2o

6x 4x6no2+8nh3 = 7n2+12h2o6y 8y

6x+6y=3

4x+8y=

It can be found by the above equation

x is y. The ratio of y and x is 3 1

Write out the two chemical equations of no and no2, let the quantity of the substance x, y, and the two equations, and solve them!

I remember that there was a reaction between no2 and no, but I can't remember exactly.

The gram crystal is mole and contains molar m ions. The molar electrons are transferred and all the metals are precipitated, indicating that the m ion has a unit positive charge, i.e., the relative atomic mass of x= is, y = (242-64-62 2) 18 = 3.

During electrolysis, the anodic reaction is 4oh - 4e - =2H2O+O2, and the cathode reaction is 2Cu2+ +4e - =2Cu. From the amount of electrons, the reaction is derived from the molar hydroxide, that is, the remaining molar hydrogen ions (hydroxide is ionized from water), with a hydrogen ion concentration of 1mol L and a pH of 0.

The electrons are transferred, and if m is +1 valence then the molecular weight is 32, if it is +2 valence then the molecular weight is 64, +3 is 96, and so on, where the molecular weight is only 64 copper. Indicating that m is Cu, and the gram crystal contains copper moles, copper is +2 valence, and x=2

Column equation: 64 + (14 + 16 * 3) x + 18y = 242, x = 2, then y = 3 anode loses electrons to generate oxygen, more h+ in the solution, acidic, according to the electrons can be calculated how much more h+, and then according to the formula to calculate the ph value.

The relative molecular mass is 242, take, so there are a total of moles of this substance, it can be seen from the chemical formula that each mole crystal contains one mole of that metal, all the metal is precipitated, and the cathode weight gain is the precipitated crystal, so the molar mass of the metal is 64g per mole, and the molar electron transfer knows that the valency of the metal is 2, saying that x is 2, and then according to the chemical formula and the relative molecular mass can calculate the content of water in the crystal, many years have not been contacted, the molecular mass of nitrogen forgot to calculate it yourself, The pH value is to calculate the concentration of hydroxide in the electrolyte, this is very easy to calculate, there is molar electron transfer, the valency of hydroxide is -1, so there are moles of hydroxide, you calculate the concentration, the formula does not want me to say, there is a book, take the logarithm.

Alas, the former high school chemistry class representative, went to college and didn't know anything.

That is, there is a metal in the solution, and the electrons are.

Then 64g of metal can lose 2mol of electrons.

Then it must be copper.

Then x=2 is found by the molar mass y=3

The loss after electrolysis is that the sulfuric acid is generated, i.e.

100ml, i.e. c(h+) = 1mol l

ph=0