The cause of CO2 is usually tested with lime water instead of NAOH solution

Because the clarified lime water reacts with carbon dioxide, white precipitated calcium carbonate will be generated;

The sodium hydroxide solution does not reflect with carbon dioxide.

Therefore, it is tested with clear lime water, but sodium hydroxide solution is used for absorption.

Lime water reacts with carbon dioxide to form calcium carbonate precipitation, and sodium hydroxide reacts with carbon dioxide but has no obvious phenomenon (the sodium carbonate produced is soluble).

Carbon dioxide passes into the clarified lime water, and will react with calcium hydroxide to produce white precipitate, which is obvious. If it is passed into the sodium hydroxide solution, a reaction will occur, but there is no phenomenon. So do not use sodium hydroxide solution.

The reaction of lime water and carbon dioxide can be observed to precipitate.

Sodium hydroxide is used to absorb carbon dioxide, because although it reacts with carbon dioxide, no obvious phenomenon can be observed, so lime water is used.

Lime water meets carbon dioxide to form white precipitated calcium carbonate. To test the existence of a substance, it is necessary to produce a phenomenon. Sodium hydroxide reacts with carbon dioxide without phenomenon, but absorbs a large amount of carbon dioxide, and is generally used as an absorbent for carbon dioxide.

Because lime water reacts with carbon dioxide to form calcium carbonate precipitates, it is easy to see...

Lime water will form precipitation, and there is no obvious phenomenon in the reaction between NaOH and CO2.

With the latter, there is no noticeable phenomenon.

This can be clearly seen with the former.

There is precipitation first.

Then after excess carbon dioxide.

The precipitate dissolves gradually.

Ca(OH)2+CO2=CaCO3 (precipitation symbol) + H2O passes carbon dioxide into the clarified lime water, and white calcium carbonate precipitation is produced.

CA(OH)2: clarified lime water.

CO2: Carbon dioxide.

CaCO3: Calcium carbonate.

H2O: Water.

CO2 + Ca(OH)2=CaCO3 +H2OC2+H2O+CaCO3=Ca(HCO3)2 If it is a small amount of carbon dioxide, it will be precipitated and generated.

A large amount of carbon dioxide is not precipitated! I don't know how to ask.

Summary. Calcium hydroxide is slightly soluble, and the content of the clear solution is small, which is not enough to absorb all CO2. It's better with sodium hydroxide!

However, it is industrially absorbed by a suspension of calcium hydroxide! First of all, the amount is enough, and secondly, it is cheaper than sodium hydroxide! The resulting CACO can also be calcined and recycled!

To evaluate the advantages and disadvantages of using lime water and NaOH solution to absorb carbon dioxide.

Calcium hydroxide is slightly soluble, and the content of the clear solution is small, which is not enough to absorb all CO2. It's better with sodium hydroxide! However, industrially, it is absorbed by the suspended vertical turbidity liquid of calcium hydroxide!

First of all, the amount is enough, and secondly, it is cheaper than sodium hydroxide! The resulting CACO can also be calcined and recycled!

Hydrogen Liang refers to the large solubility of sodium oxide, so it is used for absorption, and it reacts with carbon dioxide without obvious phenomenon, calcium hydroxide is slightly soluble in water, so it is not suitable for absorbing carbon dioxide, but it can react with carbon dioxide to generate white precipitation, the phenomenon is obvious, good, thank you, teacher.

【Experimental Scheme】(1) Sodium carbonate and calcium hydroxide react to form white calcium carbonate precipitate and sodium hydroxide, and the equation of the reaction is: Na2CO3 + Ca(OH)2 CaCO3 +2NaOH;

2) Scheme A is all responsive, but there is no phenomenon, so it cannot be identified; Scheme B turns red and therefore cannot be identified; However, C and D can have different phenomena, so the experimental objectives A and B cannot be achieved;

3) The reaction between carbon dioxide and calcium hydroxide produces calcium carbonate precipitation, and the phenomenon of reactants with sodium hydroxide, so the turbidity of the original solution in group D experiment is lime water;

Conjectures and hypotheses] If it happens to be a complete reaction, it contains only sodium chloride and calcium chloride produced by the reaction;

Reflection and Expansion] contains sodium hydroxide, which can make the phenolphthalein test solution turn red, and the phenomenon obtains a colorless, clear and transparent solution, so it is unreasonable;

Verify that the beaker may contain substances in the solution, among them.

a. The pH test paper can verify whether the solution is neutral, acidic or alkaline, so it can;

b. No matter what kind of conjecture, because they all contain chloride ions, dropwise addition of silver nitrate solution will produce precipitation, so it is not possible;

c. Because the three conjecture solutions present different properties, they can be verified by litmus test solution;

d. Copper and the three conjecture substances do not react, so they can't;

E, conjecture and if the drop of sodium hydroxide immediately turns red, it means that it does not contain hydrochloric acid, if it will produce red after a while, it means that it contains hydrochloric acid, so it can;

Therefore b and d are not;

Therefore, the answer is: [experimental protocol] (1) Na2CO3+Ca(OH)2 CaCO3 +2NaOH;

2）a、b；

3) clarified lime water or Ca(OH)2 solution;

Conjectures and assumptions】 NaCl, CaCl2;

Reflection and Expansion】 NaOH solution can make the colorless phenolphthalein test solution red, and the colorless solution cannot be obtained (reasonable answers are acceptable); ②b、d．

CO2 + Ca(OH)2 = CaCO3 + H2OCA(OH)2: relative mass. The score is:

co22naoh

na2co3

H2O if CO2 is excessive.

co2naoh

nahco3

NaOH: relative molecular mass.

If the CO2 is sufficient, it will all absorb CO2 one-to-one, and at the same mass, it must be relatively small.

The acid paraalkali neutralization reaction is an OH- and H+ reaction, and an OH-F and an H+ reaction to produce water.

It is a mole of OH- and a mole of H+ reaction, KOH only has one oh- in one molecule, NaOH is also, Ca(OH)2 contains 2 oh- in a fraction, if the mass is the same, see whose relative molecular mass is smaller, who can react more acid in the same mass.

If there are 2 oh- parts, divide the mass by two and compare.

Hope to collect the bureau closed fiber!

The chemical equation for the reaction of calcium hydroxide and carbon dioxide is: CO2 + Ca(OH)2 CaCO3 + H2O

The reason why CO2 is usually tested with lime water instead of NaOH solution is: there is an obvious experimental phenomenon between CO2 and lime water, but there is no obvious phenomenon with NaOH Therefore, there is an obvious experimental phenomenon between CO2 and lime water, but there is no obvious phenomenon with NaOH

The experimental phenomenon in device B is: the volume of the balloon increases, and the solution does not become turbid.

It can be inferred from the degree of balloon inflation that sodium hydroxide absorbs more carbon dioxide

Methods of differentiation.

The principle is that Ca ions are used to easily generate precipitates, but Na is not.

1.Carbon dioxide is introduced.

Clarified lime water will be cloudy.

Sodium hydroxide has no obvious phenomenon;

CO2 + Ca(OH)2 = CaCO3 precipitate + H2O.

2.Just drop in sulfuric acid.

The phenomenon is as above; H2SO4 + Ca(OH)2 = CaSO4 precipitate + 2H2O.

Sodium carbonate is used to distinguish it.

Ca(OH)2+Na2CO3=CaCO3 NaOH calcium carbonate will precipitate.

Therefore, after the reaction, there is a white precipitate of calcium hydroxide (lime water), and the one that does not react is sodium hydroxide.

There are more methods.

The principle is that Ca ions are used to easily generate precipitates, while Na is not good1Carbon dioxide is introduced.

Clarified lime water will be cloudy.

Sodium hydroxide has no obvious phenomenon;

CO2 + Ca(OH)2 = CaCO3 precipitate + H2O2Just drop in sulfuric acid.

The phenomenon is as above; H2SO4 + Ca(OH)2=CaSO4 precipitate + 2H2O without formulator.

We'll see.

Same as SO2

Orco2 produces lime water that produces white precipitates.

co2+ca(oh)2

caco3+h2o

Add salts containing CO32-.

Such as na2CO3

ca(oh)2=caco3+2naoh

A white precipitate is generated.

a. Because the magenta solution is tested for sulfur dioxide, A is wrong;

B. Because no matter whether CO2 is mixed or not, white precipitate will not be produced, SO2 and CO2 are in the same solution as NaOH: 2NaOH + SO2 Na2SO3 + H2O, 2NaOH + CO2 Na2CO3 + H2O, so B is wrong;

C. Because no matter whether there is CO2 or not, white precipitate will be generated: CO2 + CA (OH) = CA CO3 + H2O, SO2 + CA (OH) = CASO3 + H2O, can not verify whether there is CO2, so C is wrong;

D. KmNO4 acidic solution will completely absorb SO2, if there is a white precipitate, there must be CO2, if there is no precipitation, there is no CO2, so D is correct;

Therefore, d

The vinegar in the kitchen is the aqueous solution of acetic acid, and the solute of paraffin and gray water used to test carbon dioxide in the laboratory is calcium hydroxide;

Using gasoline to wash off the oil stains on your hands is to use gasoline to dissolve the oil stains to form a solution to achieve the purpose, and the liquid bureau uses the dissolution principle;

Detergent has an emulsifying effect, which can divide large oil droplets into a mess and let the small oil droplets be washed away with water, which is the use of emulsification

So the answer is: acetic acid; Calcium hydroxide; Dissolve; Emulsify.