When SO2 is passed into the following solutions, what must not have precipitated at the end?

Only A, if A has a precipitate, then it is BaCl2 + SO2 + H2O = BaSO3 + 2HCl

In fact, the reaction is reversed because HCl is more acidic than H2SO3.

B first has 2NH3 + SO2 + H2O=(NH4)2SO3, then BACl2+(NH4)2SO3=BASO3 +2NH4ClSO2 excess, and then BaSO3+SO2+H2O=BA(HSO3)2C HNO3 will oxidize SO2 to make it become H2SO4, and then there is BACL2+H2SO4=BASO4 +2HCLD Ca(OH)2+SO2=CaSO3 +H2O, and there is CaSO3+ in excessso2+h2o=ca（hso3）2

a Baso3 precipitate was generated.

b The BASO3 precipitate is reacted with ammonia.

c The resulting precipitate is oxidized by nitric acid to BaSO4

d caso3 precipitation. Pick B

b wrong. Correct Answer: a

There is no precipitation. Because sulfurous acid is not as acidic as hydrochloric acid.

It is not possible to make weak acid from strong acid.

BBA barium sulfite.

c Barium sulfate. d Calcium sulfate.

Why B? LS's answer.

Teacher Ena also gave us an example.

A Yes, the above is very detailed.

The phenomenon of sulfur dioxide penetrating into the barium chloride solution is produced by white precipitation. When SO2 is introduced into the BaCl2 solution, part of the SO2 reacts with the water in the solution, and the generated H2SO3 is oxidized to H2SO4 by the O2 dissolved in the solution, and H2SO4 reacts with BACl2 to form a BaSO4 precipitate.

The reaction process is: SO2 + H2O = H2SO3, 2H2SO3 + O2 = 2H2SO4, H2SO4 + BACL2 = BASO4 + should come from air, and the longer the preparation time, the more oxygen dissolved in the BaCl2 solution, the more turbidity is likely to occur after the introduction of sulfur dioxide gas. In addition, the prepared SO2 may also be mixed with air.

Properties of sulfur dioxide:

At room temperature, moist sulfur dioxide reacts with hydrogen sulfide to precipitate sulfur. At high temperature and in the presence of a catalyst, it can be reduced by hydrogen to hydrogen sulfide and carbon monoxide to sulfur. Strong oxidizing agents oxidize sulfur dioxide to sulfur trioxide, which can only be oxidized to sulfur trioxide by oxygen in the presence of a catalyst.

It has spontaneous combustion, non-combustibility. Liquid sulfur dioxide can dissolve organic compounds such as amines, alcohols, phenols, organic acids, aromatic hydrocarbons, etc., and most saturated hydrocarbons cannot be dissolved. It has a certain water solubility, and reacts with water and water vapor to form toxic and corrosive vapors.

The above content reference: Encyclopedia - sulfur dioxide.

Pick C; Because:

If a precipitated hail draft can be generated, then the reaction should be SO2+CaCl2+H2O==CaSO3+2HCl

This will be a weak acid to strong acid process, but CaSO3 is not a precipitation like Baso4 and AGCL, which is insoluble in acid and insoluble in water, and does not meet the conditions for the metathesis reaction to occur, because HCl can be reversed with CaSO3 (and vice versa), so the reaction cannot occur!;

The reaction in b to generate Na2SO3 is soluble Tongxiao;

C: Ca(OH)2+SO2=CASO3 +H2O;

The equation in d: SO2 + 2FeCl3 + 2H2O = FeSO4 + FeCl2 + 4HCl, no precipitation is generated.

Option DA BA(OH)2 + SO2 = H2O + BASO3(precipitation).

Item B, NO3- is oxidizing in acidic solution, and BASO3 can be oxidized to BASO4, which is insoluble in acid

3ba(NO3)2 + 3SO2 + 2H2O = 2NO + 4HNO3 + 3BASO4 (precipitate).

Item C, centering reaction 2Na2S + SO2 + 2H2O = 4NaOH + 3S (precipitate).

D, the H2SO3 formed by SO2 dissolved in water is a weak acid and will not metabolize with the barium salt of the strong acid.

Choose D because BaSO3 is soluble in acids and will not precipitate in acidic solutions.

A solution is alkaline, so Baso3 can be precipitated, B solution acidic NO3- can oxidize Baso3 to Baso4 to precipitate, C: S2- and SO2 react to form sulfur precipitate.

There's no option, there's no way to do it.

The former does not precipitate, the latter does.

SO2 is introduced into BACL2 solution or BA(OH)2 solution, and SO2 first reacts with water: SO2 +H2O-==H2SO3. H2SO3 cannot continue to react with BaCl2.

Because BaSO3 dissolves in the resulting hydrochloric acid, the following reaction does not occur: H2SO3 + BACL2==BaSO3 +2HCl

This is different in the Ba(OH)2 solution, where H2SO3 can generate a BaSO3 precipitate because there is no acid formation:

h2so3+ba(oh)2===baso3↓+2h2o

Sulfur dioxide must not sink into barium chloride to form at the bottom, because if barium sulfite precipitate is generated, hydrochloric acid will also be generated, so it will not react.

There must be a precipitate in barium hydroxide, because the barium sulfite produced also produces water, so it will not have much effect.

If SO2 is introduced into the BACL2 solution, will there be precipitation?

No, if you put it into the Ba(OH)2 solution, there is no precipitation.

Yes, the general precipitation disappears.

Sulfur dioxide is introduced into the barium chloride solution until it is saturated and there is no precipitation, indicating that the original solution is acidic and cannot form barium sulfite precipitation. There are two ways to get a precipitate. 1. To neutralize the acid, alkali or alkaline gas (such as ammonia) can be added.

2. Oxidizing sulfite into sulfate, oxidizing agents (such as nitric acid, ozone, chlorine, etc.) can be added. To sum up, choose D for this question

BA generates a precipitate.

C NO3- encounters H+ into nitric acid, oxidizes SO32- into SO42- microsolute, and precipitates D with C

a；Analysis: According to the reaction equation, the following judgment can be made:

A, 2Na2S + SO2 + 2H2O = 3S + 4NaOH, redox reaction, the formation of precipitate, and the precipitate is insoluble in sulfurous acid;

b、bacl2+so2+h2o=baso3↓+hcl；

The resulting precipitate dissolves in acid (barium sulfite will dissolve in the resulting hydrochloric acid), so this reverse osmosis chain should not occur; Therefore, there will be no precipitation in this solution;

c、so2+2fecl3+2h2o=h2so4+2fecl2+2hcl；

Redox reaction, no precipitation generation;

D. Ca(OH)2+SO2=CASO3 +H2O (a small amount of SO2, generating precipitation);

CaSO3+SO2+H2O=2CaHSO3 (excess SO2, precipitation dissolves);

Therefore, when there is an excess of SO2, there will be no precipitation;

Analysis: a na2s

Na2S + SO2 + H2O (a small amount) Na2SO3 + H2S

2H2S + H2SO3 (sufficient) 3S +3H2O

b bacl2

bacl2 + so2 + h2o → baso3 + 2hcl

However, BaSO3 will be soluble in HCl, so it does not react.

c fecl3

2FeCl3 + 3SO2 + 3H2O Fe2 (SO3) 3 + 6HCl

However, BaSO3 will be soluble in HCl, and Fe3+ and (SO3)Mopwang2- will be dihydrolyzed and cannot coexist

2fe3+ +3（so3）2- +3h2o → 2fe（oh）3↓ +3so2↑

So do not react. Danzai.

d ca（oh）2

Ca(OH)2 + SO2 (a small amount) CaSO3 + H2O

Precipitate dissolves: CaSO3 + SO2 + H2O Ca(HSO3)2

So in the end, no precipitation will be generated.

In summary, only A produces precipitation.

So choose A.

It's better to ask the teacher directly, and you can make a good impression! After graduating, I have returned it to the teacher for many years.