Judging Right and False Chemistry and Life, Chemistry Judging Right and False

It can be (1) (2) (3).

Example: 1) Fe+CuSo4=Cu+FeSo42) Cl2+2Ki=2KCl+I2

3) 2Na+2H2O=2NaOH+H2 (sodium can react with salt solution, but the essence is to react with hydrogen ions in water to replace hydrogen).

4) No, because a reducing agent is required to replace the metal from the salt solution, and the non-metal elements are very few in themselves (such as H2, C, etc.), and there is basically no reaction with the salt solution.

1.Zinc displaces copper from a solution of copper sulfate.

2.Chlorine can be replaced with bromine from sodium bromide.

3. Zinc can replace hydrogen from sodium bisulfate.

4.For example, if it can be replaced, the valency of metals will decrease, and the non-metals will rise, and if they exist, they should react with water first.

1 pair, the metallicity of x is stronger than y, and it is possible to hold at this point (e.g., fe displaces cu in cu salt solution).

2 pairs, the non-metallic activity of x can occur when the non-metallic activity of y is stronger than that of y (e.g., chlorine gas displaces bromine in potassium bromide solution).

3 pairs, this kind of reaction can still be encountered in secondary school (e.g., 2Na + 2NaHCO3 = 2Na2CO3 + H2) but it would be wrong to say that Y is replaced by the salt solution of Y.

4. No, the replacement of metal elements by non-metallic elements is generally no longer the reaction in salt solution, and the reaction is mostly solid and gas reaction.

This is wrong, the right one should be:

5SO2 + 2S2- +2H2O = 3S (precipitation) + 4HSO3 -

Your product is misjudged.

No, there is no need to put a gas symbol on the back, because the sulfur dioxide introduced in front is a gas.

Answer] D Answer Analysis] Question Analysis: 70 75 alcohol can denature proteins, so it is used for medical disinfection. Vinegar can denature proteins, so when the flu infection is severe, vinegar can be smoked to prevent and disinfect.

NaCl can inhibit the growth of certain bacteria, so it can be used as a preservative to pickle foods. If the combustion of liquefied petroleum gas is insufficient, toxic gases such as CO will be produced. Therefore, it is not possible to eliminate kitchen pollution.

The answer is D. Test Focus: Chemistry and Life.

Comment: This question is very simple and basic.

The addition of sodium acetate crystals is increased, and the addition of sodium acetate to CH3COO- +H+ *****CH3COOH increases the concentration of CH3COOs, shifts the equilibrium to the right, decreases the concentration of H+, and increases the concentration of OH ions.

Dilute H2O*****H+ + OH- with water on the surface, the equilibrium shifts to the right and the OH concentration rises, but the multiplier of the dilution with water is much larger than the amount increased by the equilibrium shift, so it should be reduced.

Doesn't grow.

Because weak acids and weak alkali salts form a buffer solution, the pH of the solution remains constant under certain conditions, so the hydroxide concentration remains the same.

Yes, because CH3COOH is a weak acid, it will exist in molecular form, reducing the H+ ions in the solution and thus increasing the relative (OH-).

Answer D analysis: 70% alcohol has the best penetration effect on bacterial proteins; The active ingredient of vinegar is acetic acid, which has a bactericidal effect; Sodium chloride has a salty taste and is often used as a condiment and preservative, and the use of liquefied gas can reduce pollution but cannot eliminate pollution

Answer: a. Practice has proved that 70% alcohol has the strongest permeability and the best bactericidal effect, so A is the strongest;

B. Vinegar can sterilize, in order to prevent influenza infection, the classroom doors and windows can be closed, fumigated with vinegar for disinfection, so B is the strongest;

c. Sodium chloride is commonly used as condiments and preservatives, so C is correct;

d. The use of liquefied gas can reduce pollution, but it cannot eliminate pollution, so D is wrong, so D is chosen

Comments: This question examines the uses of common substances, and the completion of this question can be based on the properties of the substance

a Acetylene, ethylene, acetaldehyde, toluene, formic acid, ethanol can fade;

b Acetic acid, polyethylene cannot;

Acetylene, structural formula h-c c-h, chemically active, can cause addition, oxidation, polymerization and metal substitution reactions; Oxidized by KMno4: can fade the purple acidic potassium permanganate solution. C2H2 + 2kmNO4 + 3H2SO4 2CO2+ K2SO4 + 2MnSO4 + 4H2O, is an oxidation reaction.

Ethylene, simple structure: ch2=ch2, is easily oxidized by oxidant at room temperature. If ethylene is introduced into an acidic KMNO4 solution, the purple color of the solution fades and ethylene is oxidized to carbon dioxide, which can be used to identify ethylene.

Polyethylene, structural formula CH2=CH2+CH2=CH2+·· ch2—ch2—ch2—ch2···

Polyethylene is susceptible to photo-oxidation, thermal oxidation, and ozone decomposition, but its structure is very stable and is not oxidized by potassium permanganate.

Toluene Molecular Formula: C7H8, Toluene can be oxidized by KMno4 to benzoic acid.

Ethanol structure simplified: C2H5OH

Ethanol can also be oxidized by potassium permanganate, while potassium permanganate changes from purplish-red to colorless.

Acetaldehyde structure simplified: CH3CHo

According to the principle of redox reaction, potassium permanganate is a strong oxidizing agent and can certainly oxidize acetaldehyde to acetic acid.

Formic acid, structure simplified: HCOOH

The hydrogen atom in formic acid and the carbon-oxygen double bond form an aldehyde group, which is reducible and can be oxidized by the acid potassium permanganate to obtain carbonic acid, which is then decomposed into water and carbon dioxide.

Acetic acid, CH3COOH

There is no aldehyde group structure in acetic acid, so it cannot.

For cracking gasoline, pyrolysis gas, coke oven gas (all have unsaturated hydrocarbons, can be added with bromine water), crude ammonia water (bromine water is acidic, neutralization reaction with ammonia water), carbolic acid (substitution with bromine water to generate tribromophenol).

CCL4 (extraction).

Acetylene, ethylene, acetaldehyde, toluene, formic acid, acetic acid. Contains unsaturated bonds that fade KMNO4(H+)(AQ).

Ethanol is reducible, so that.

KMNO4(H+)(AQ) fades.

Polyethylene doesn't.

This statement is wrong. Polyethylene and acetic acid can not fade KMNO4 (H+) (AQ), and acetylene, ethylene, toluene, ethanol, acetaldehyde and formic acid can fade KMNO4 (H+) (AQ).

Wrong, ethanol doesn't work, and neither does polyethylene.

Even acids can't be returned, but alkaline materials can't be returned.

NH4Cl, AGNO3 and NaOH are mixed to obtain a clear solution, which must be the silver chloride precipitated by the reaction of silver ions and chloride ions dissolved in the ammonia water generated by the reaction of ammonium ions and hydroxide ions to generate soluble silver ammonia complex ions. Silver ammonia ions can be destroyed by hydrogen ions to form silver ions and ammonium ions, and silver ions react with chloride ions to obtain acid-insoluble silver chloride precipitates.

So that's true.

It doesn't seem right, this solution is not a clear solution, it should be a white precipitate, AGCL

False: Mr. into silver hydroxide ammonia, is a white precipitate, but continued to add will make the silver hydroxide diaminohydrate dissolve.

C(H+) = 10 -11 produced by ionization of water in alkaline solution with xph = 11

Pure water ionization yields c(h+) = 10 -6

So it should be 1 10000

C(H+) = 10 -11 Pure Water Ionization produced by water ionization in alkaline solution with pH = 11 at room temperature = 10 -7, the ratio of the two is 10 4 times, that is, 10000 times.

Explanation: In alkaline solution with pH = 11 at room temperature, c(oh-) = 10 -3, according to kw = 10 -14 = c(h+) * c(oh-).

Find out that C(OH-)=C(H+)=10 -11 of water ionization, no matter what solution, the concentration of hydrogen ions and hydroxide ions ionized by water is always equal.

Pure water c(oh-) = c(h+) = 10 -7

ErrorC(H+)=10 (-11) produced by water ionization in alkaline solution with pH=11 at room temperature

Pure water ionization at room temperature produces c(h+)=10 (-7).

Therefore, the c(h+) produced by water ionization in a alkaline solution with pH=11 at room temperature is 10 (-4) of the c(h+) produced by pure water ionization, i.e., 1 10000

Wrong. In this case, the hydrogen ion concentration should be 10 minus 11 mol l and pure water is 10 minus 7 ml, so it's the other way around.