Senior 1 Chemistry Removal Problems, High School Chemistry Removal Problems Summary

It reacts with HCl and Cu does not react with HCl, so Cu2 is obtained by filtering after adding dilute HClAdd an appropriate amount of dilute HCl, and react sodium carbonate with hydrochloric acid to form sodium chloride.

3.When NaOH solution is added, acidic H2S reacts with NaOH while H2 does not.

4.Add an appropriate amount of calcium hydroxide, and the sodium carbonate reacts with calcium hydroxide to form calcium carbonate precipitate, which can be filtered.

1.Dilute sulfuric acid, filter, the activity of H2SO4+Fe=FeSO4+H2 Cu after H, does not react with dilute sulfuric acid.

2. Excess dilute hydrochloric acid, heating HCl and Na2CO3 reaction to generate NaCl and CO2 H2OHeating allows the excess HCl gas to escape.

3.Passage into CuSO4 solution CuSO4+H2S = CuSO+H2SO4 H2 runs out.

Or add NaOH solution, acidic H2S will react with NaOH to form Na2S while H2 will not.

4.Calcium hydroxide solution. Filtration. The generated caCO3 is removed by filtration.

1.Add hydrochloric acid. Fe will reflect and Cu will not. Then filter the remaining Cu2Add HCl

3.Saturated NAHS

4.Calcium hydroxide added. White precipitate. Filtered out is sodium hydroxide.

1.To remove Fe from CU, add HCl (excess) or use a magnet.

2.To remove sodium carbonate from sodium chloride plus HCl (excess)3To remove hydrogen sulfide from hydrogen gas is passed into concentrated H2SO44To remove sodium carbonate from sodium hydroxide, add Ca(OH)2 (excess).

1. Dilute hydrochloric acid can be used, hydrochloric acid can react with iron, not with copper 2, sodium chloride can be produced by hydrochloric acid, hydrochloric acid and sodium carbonate reaction.

3. Absorb hydrogen sulfide with sodium hydroxide aqueous solution.

4., add calcium hydroxide.

1.Dilute sulphuric acid or magnetite.

2.Sufficient amount of hydrochloric acid before heating.

or copper sulfate solution.

4.Lime water to taste.

It is recommended that you go to the bookstore to find such revision materials, which can help you more effectively.

Do more questions, in the questions will contain almost all the knowledge points in high school books, and if you do more, you will naturally have experience.

1、co2

h2sso2

What reagents are used in addition to HCL in Cl2, why, why can't similar reagents, for example: saturated NaHCO3

and saturated Na2CO3...

co2(hcl)

Saturated NaHCO3 is used in addition to HCl, HCl+NaHCO3==NaCl+CO2+H2O, CO2+H2O+

na2co3

2NaHCO3, unsaturated NaHCO3 will also absorb CO2, so saturated NaHCO3 is used.

h2s(hcl)

In addition to HCL, NaHS is used, HCl+NaHS==NaCl+H2S.

so2(hcl)

In addition to HCL with saturated.

nahso3

HCl+NaHSO3==NaCl+SO2+H2O, the reason is the same as CO2.

cl2(hcl)

In addition to HCl, saturated salt water is used.

2. Why do you use NaOH instead of Ca(OH)2 to remove CO2 from CO?

Ca(OH)2 solubility is too small to absorb much CO2, and CaCO3

It is also a precipitation, which is sticky in the water, which is not conducive to the removal of impurities from gases.

3. Why is saturated salt water used for HCl in Cl2?

Because there are chloride ions.

The loss of chlorine dissolved in water can be minimized, and only a small part of chlorine will be dissolved, except for HCl, because HCl

Extremely soluble. In terms of water, saturated salt water is mainly water.

4. Why is saturated NaHCO3 used for SO2 in CO2?

The reason is the same as CO2 (HCL).

In addition to HCl, SO2+NaHCO3==NAHso3+CO2.

1. In fact, to remove impurities is to leave what you want in a mixture and remove what you don't want. It is necessary to find a way to make a thing react with impurities and not with the target substance. For example:

If you want to remove iron powder from copper powder, the target substance is pure copper powder, and the impurities are iron powder. So what can react with iron powder and not with copper powder?

You will analyze that it can be hydrochloric acid!

Because copper is a post-hydrogen metal, it does not react with acids.

But it can react with iron. Then the iron becomes ferrous chloride and dissolves in solution, and the copper powder is still insoluble, so it is separated by filtration.

I think you can develop your interest in chemistry by doing this, and you won't have to worry about memorizing those methods.

Can be deduced for yourself.

In fact, there is an easier way to remove impurities.

It's just with magnets!

Just suck the iron powder out, and that's fine.

Therefore, I think you should analyze each question in detail, and ask the teacher if you don't understand. Instead of memorizing methods and types, anyway, the methods are varied.

It's OK to do more questions in this way

In addition to the impurities in the substance, the specific problems should be discussed in detail, but the general routine and basic standards will not change.

To remove impurities, you can use washing gas, filtration, dispensing, distillation, etc. However, some chemical reagents will be used in some impurity removal processes, so it is necessary to pay attention to the fact that the chemicals used cannot react with the substances to be obtained to avoid bringing in new impurities.

In addition to impurities, you either get out the impurities, or you can get out the substances you want to get, and the specific methods are the methods I mentioned above.

The principle of impurity removal in B is the use of redox reaction, the principle of impurity removal in C is to use the solubility of the two substances to change differently with the change of temperature, and D uses the difference in the boiling point of the two.

I choose a...A - this new impurity is introduced.

It is feasible in B, CO2 does not react with acidic potassium permanganate and concentrated sulfuric acid, and SO2 can be oxidized by acidic potassium permanganate solution. It can be reached.

c Feasible. Because the solubility of potassium nitrate varies greatly with temperature, and the solubility of sodium chloride varies little with temperature, potassium nitrate crystals can be precipitated from the hot solution by crystallization.

D is also feasible, add CAO and CH3COOH reaction, the generated (CH3COO)2Ca is a precipitate, filtration, distillation can obtain absolute ethanol.

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Adding barium chloride first will cause barium ion residue, and then adding sodium carbonate excessively, while precipitating barium ions and calcium ions, although carbonate will remain, but the impact will be smaller than barium ion residue.

Sodium carbonate is added first, followed by barium chloride, which will cause barium ion residues.

There is some truth to your understanding.

But in addition to qualitative analysis, there is also a quantitative problem involved in your method: how can you ensure that the FeCl3 you add will make the aluminum exactly react completely? The aluminum in the iron powder, the iron is a large amount, the aluminum powder is a small amount, and some of the iron must be consumed due to the reaction.

So this method is not optimal.

The principle of removing impurities: while removing impurities, it is required that no new impurities are introduced.

It is recommended to choose NaOH, which can only react with aluminum and not with iron.

The reaction equation is:

2al + 2naoh + 2h2o = 2naalo2 + 3h2↑

In general, excessive reagents are added to remove impurities, so excess FeCl3 must dissolve part of Fe In this way, the Fe is also lost while removing impurities, and I don't know under what circumstances the excess is over, how to ensure that the impurities are removed?

So no.

Oh, what you said makes a lot of sense Fe3+ has oxidizing properties so it can react with Fe, but Al also has reducibility, and it is stronger than Fe Al+3Fe3+=Al3+ +3Fe2+

It cannot be controlled in the test, just add NaOH solution, Al can react with NaOH to produce sodium metaaluminate and dissolve in water The rest is iron powder, and pure iron is obtained by filtration.

At the same time, aluminum can also react with ferric chloride, because aluminum has strong reducing properties, and ferric chloride has strong oxidation, and the two react.

3FeCl3+Al=2FeCl2+AlCl3, in this case, your previous iron powder is consumed in vain, so it does not meet the requirements for impurities.

To remove the aluminum in the iron powder, you can use sodium hydroxide solution, filter out the iron after full reaction, and wash it.

Because ferric chloride will also react with aluminum: 3FeCl3 + Al=2FeCl2 + AlCl3, it will consume iron powder and do not meet the requirements of impurities.

Don't understand what you're asking? Won't your iron powder be reduced if you add ferric chloride? Adding ferrous chloride can go out, and aluminum can also increase the quality of iron.

Because iron is more reducible than aluminum, iron will first reduce Fe3+ to Fe2+

The point is that in the end it is not good to remove it completely.

Use the characteristics of AL that can react with alkali to remove impurities

Is it the introduction of new impurities?