Three chemistry questions, illustrate the correctness and falsehood, please give examples, thank you

Answer]:1The more electrons are obtained, the stronger the oxidation is false] The strength of the oxidation has nothing to do with the number of electrons gained. It has nothing to do with the difficulty of electronics.

Examples: S and CL

2.The elemental element can be prepared by oxidizing or reducing the compounds of the element, right] 2NaCl = 2Na + Cl2 (electrolytic) Na : 1---0 . is restored.

cl ：-1---0 。is oxidized.

3.Cations can only get electrons to be reduced, and can only be oxidantsWrong] Cations can also lose electrons and be oxidized, and they can also be oxidants.

For example: Fe2+ + HnO3 and other strong oxidants) --Fe3 + 4The compounds that contain the most ** do not necessarily have strong oxidizing properties.

Pair] CO2, dilute sulfuric acid, etc.

1.Error Fluorine and oxygen.

2.True, electrolysis can also be regarded as redox.

3.Error ferrous ions.

4.Correct carbon dioxide.

1 Wrong s and CL

2 pairs of S H2S oxidation of S SO2 reduction yields S3 pairs, Fe2+ can be both raised and decreased.

4 pairs of S O2 can oxidize it.

1.Wrong. The dilute nitric acid reaction is the formation of nitric oxide. The concentrated nitric acid reaction is the formation of nitrogen dioxide.

Obviously, concentrated nitric acid is more oxidizing than dilute nitric acid.

2.Probably right - not quite sure. Because it is impossible to cite counter-examples.

3.Wrong. Nitrogen dioxide can be turned into nitric acid.

4.Right. Sodium chloride.

1 Select sensitive foci.

2 Slightly cherry blossoms returned.

3 cuso4 ，h2so4

4 c and d which c should be the filtrate not the filter residue, where is the 2 filter residue.

5 Fe2+ is oxidized by air to Fe3+, and then Fe3+ water ridge starvation produces Fe(OH)3 precipitation.

1.The quantity, concentration and volume are the same, which means that the amount of the substance is the same.

This involves the problem of hydrolysis, the acid cannot make K2CO3 react, but can only turn the carbonate into bicarbonate, so the hydrolysis is alkaline.

Quicklime reacts with water, consumes water and is exothermic, solubility decreases, and solids precipitate.

Returning to the original temperature means that the solubility is increased to the original level, but there is less water, so Ca2+ is reduced.

But the solution is still a saturated solution, so the concentration is constant, and the pH is constant.

To be honest, D I think it's also true, adding NaOH will increase the concentration of OH- and it will also exothermic, both of which will precipitate Ca(OH)2.

The solubility is very small, and it is completely negligible to add only a little water, but it can be understood as this way now, and there will be other situations in the future.

4.This is related to the production of weak acids by strong acids, that is, the acidity in the product is less than the acidity of the acid in the reactants, which can be seen in this question.

But if there is no H+, there will be no strong acid, so C is okay.

d is the same thing.

However, if there is a redox reaction in the reaction process, which is a valency change, it is not necessarily.

1. Potassium carbonate, HCl, and calcium chloride will react to generate 1:1 carbonate and H ions, but these two react 1:2, so the H ions are consumed, and half of the carbonate anions, which are weak acid anions, produce CaCO3 precipitation, so according to the theory of high school textbooks, they should not be chosen.

But I would like to say that when we did this experiment in our undergrad, the pH was indeed slightly greater than 7, which was ignored in high school.

2. C and D3: Do you consider complexation in your high school? If you don't think about it, the concentration will change. The answer is wrong (in other words, your answers are hundreds of questions that we graduate students do in half a day...) Can't believe it too much).

4. Let's talk about A: If you think that the reaction must be to generate ferrous sulfide, but in this case, the other product is hydrochloric acid, and the production of hydrochloric acid with hydrogen sulfide is a weak acid to a strong acid, which is not kineticly feasible.

Again D: The reason is the same as above, redox reaction cannot occur. Carbonic acid is stronger than hydrogen sulfide.

1. The amount of potassium carbonate, HCl and other substances reacts to generate potassium bicarbonate and basic salts, so the pH is greater than 7.

2, c, the original solution is a saturated solution, then the addition of quicklime, still can not change the situation of the saturated solution when the solution, the same is a saturated solution, the amount and concentration of the substance of the solution, the mass fraction and so on will not change, so ab is not right, adding sodium hydroxide, will not affect the solubility of calcium hydroxide, so there will be no precipitation, so d is not right.

3. AGCL is a white insoluble acid precipitate, and the solubility is basically negligible, so adding a small amount of water will not affect the solubility, or the impact can reach a negligible degree.

4, A, Fes is soluble in acid, the reaction can not occur, does not meet the conditions of weak acid to strong acid. Weak acids make strong acids, which must be insoluble in acid precipitation.

D can't react to CO2, otherwise the reason is the same as A.

You should understand.

Carbonate reacts with H+ and calcium ions to produce bubbles and precipitation Neutral quicklime chemical reaction requires water Water is less Water dissolved calcium hydroxide is less Sodium hydroxide is added due to precipitation dissolution balance More hydroxide There are fewer dissolved calcium ions The third one does not know.

Fourth, if you write the chemical equation, you can see that there are substances on the right side of the equation that can't coexist, so either there's no reaction at all, or the equation is wrong, or there's no reaction.

The 1st floor is a university to listen to your tone. But. You read it in vain.

The second floor is correct.

1. Carbonate and H+ ions form unstable carbonic acid, and 1mol carbonate needs 2mol of hydrogen ions, because of the amount of concentration of equal volume and other substances in the solution, so the carbonate is 1mol, and the hydrogen ions are also 1mol, and the hydrogen ions are not enough, so the hydrogen ions in the water should be snatched up, and the hydrogen ions in the water are less, and it will be alkaline.

2. Adding quicklime is equivalent to the reaction of water and quicklime to generate calcium hydroxide, because it is originally a saturated calcium hydroxide solution, after the reaction, there is less water and more calcium hydroxide, and calcium hydroxide will be precipitated. Because it is saturated, it is still saturated after the reaction, but the total amount of the solution is reduced, so the number of A and Ca+ must be reduced. b. The concentration is constant.

c. The pH value is also constant. D. Sodium hydroxide is added, that is, hydroxide is added, and the amount of Ca+ does not increase, so calcium hydroxide will not be precipitated.

3. I really don't know this, it doesn't make sense.

4. a. Hydrogen sulfide is introduced, because only strong acid can make weak acid, and if precipitation is generated, hydrochloric acid will also be generated, and hydrogen sulfide is weaker than hydrochloric acid, so the reaction equation is not established. b. No need to explain. c. Because there is no restriction of strong acid and weak acid, ferrous sulfide precipitation is naturally generated.

D. Carbon dioxide enters the water and rises into carbonic acid, but there are chloride ions, so like A, hydrochloric acid must be generated if you want to generate precipitation, which is obviously not as acidic as hydrochloric acid, and it cannot react.

All wrong. Examples:

2。The chemical reaction is a combination of reactants to produce one product: 2H2+O2==2H2O (chemical counter-posture disorder) counterexample H2CO3==H2O+CO2

Splitting the file to solve the reaction.

The displacement reaction is: elemental + compound hail hall = = another elemental substance + another compound.

The neutralization reaction is: acid + base = salt + water.

The decomposition reaction must have elemental formation: CaCO3 = high temperature = Cao + CO2 All reactions with compound formation are chemical reactions: Cu(OH)2= =CuO+H2O

The reaction with the formation of elements and compounds must be a decomposition reaction: 3O2 = discharge = 2O3 The oxidation reaction must be a chemical reaction: CH4 + 2O2 = ignition = CO2 + 2H2O

CaCO3 = High Temperature = Cao + CO2 gas symbol.

hcl+naoh==nacl+h2o

H2 + Cuo = Heating = Cu + H2O

3no2+h2o==2hno3+no

1 All (1)2 NaHCO3 == == Na2CO3 + CO2 + H2O has no elemental substance.

2) NaCl + Agno3 = AgCl + Nano3 has compound formation, but it is a metathesis reaction.

3) 2H2O2 ==MNO2== 2H2O + O2, which produces both compounds and elementals, but it is a decomposition reaction.

4) This is a decomposition reaction.

(1) h2co3=co2↑+h2o

2) The above reactions can still be used as counterexamples, as well as the decomposition reactions of potassium permanganate, potassium chlorate, and hydrogen peroxide.

3) CO+CuO=Heating=Cu+CO2(4)CO2+2NaOH=Na2CO3+ H2O

CaCO3====CaO+CO2 equal sign has high temperature NaOH + HCl = NaCl + H2OCO+Cuo ==Cu + CO2 equal sign on top and high temperature Ca(OH)2 + CO2 ====CaCO3 + H20