Chemistry In the following reactions, among the following groups of chemical reactions, which are th

One metal with many acids:

It is basically impossible to tell, because the acids are mixed, and it can be a reaction between metals and H+.

One metal and multiple salts: If it is a very reactive metal, such as potassium, calcium and sodium, it reacts with water first and then carries out other reactions.

If the metal is not very reactive, if it can be replaced, the displacement reaction will occur.

A mixture of an acid and a variety of bases (or vice versa):

All of them are acid-base neutralized, which is difficult to judge.

One salt with multiple acids or bases: In the same way, mixing acids and bases does not have the need to discuss sequential reactions, nor does it make sense.

A mixture of one salt and a mixture of salts: if a precipitate is formed, the one with the least solubility is formed. If gas or water is generated, there is no need to discuss it, it is basically generated at the same time.

If there is CaO and CaCO3 in the reactants, will CaO react with the water in the solution first if an acid solution such as dilute sulfuric acid is added?

The answer is: Yes. The reaction of CAO and H2O is inherently easy to occur.

The resulting Ca(OH)2 is then neutralized with dilute sulfuric acid, and the remaining acid reacts with CaCO3. In fact, there is no need to discuss this kind of problem, this situation can only show that the amount of acid that reacts with CACO3 is less, which is not meaningful. You don't have to dig into it.

React according to the metal activity sequence table.

If Mg is put into a mixed solution of Al2(SO4)3 and ZnSO4, MG will first react with Al2(SO4)3.

No. Calcium oxide is too much to react with water.

CaO, which reacts with water to produce Ca(OH)2 and then reacts with H2SO4 to produce water, can be regarded as sulfuric acid directly reacting with CaO.

a.hydrolysis of bromopropane to propanol (substitution reaction); Propanol is produced by the reaction of propylene and water (addition reaction).

b.Nitration of toluene to p-nitrotoluene (substitution reaction) and oxidation of toluene to benzoic acid (oxidation reaction) cChlorocyclohethane elimination to cycloethane (elimination reaction) and propylene plus bromine to 1,2 dibromoethane (addition reaction).

d.Ethyl acetate from acetic acid and ethanol (substitution reaction) and benzoic acid and ethanol from ethyl benzoate hydrolysis (substitution reaction).

A substitudes the addition B substitutes, oxidizes the c, and removes the addition.

As long as the equation of d is still?

The equation for the reaction of A Na2O 2 with a sufficient amount of SO2 is: Na 2O 2+SO2=Na 2SO4, from the equation, it can be seen that 1 mol Na2O 2 reacts with a sufficient amount of SO2, the SO2 participating in the reaction is 1mol, the sulfur element is from +4 valence +6 valence, and the transfer electrons are 2mol, so A is wrong;

B According to an important law of metathesis reaction: relatively strong acid can make relatively weak acid, so vinegar can dissolve calcium carbonate in scale, calcium carbonate is a precipitate, when writing the ion reaction equation, the chemical formula should be written, and the ion reaction equation is: 2ch 3cooh + caco 3 ca 2++2ch 3coo -+h 2o+co2, so b is correct;

c The principle of sulfur dioxide prepared in the laboratory is: SO3 2-+2H+=H2O+SO2, Na2SO3 solution can react with dilute H2SO4 to generate sulfur dioxide, but the generated sulfur dioxide dissolves more and escapes less, so C is wrong;

D Cu reacts with concentrated Hno 3, and concentrated Hno 3 is reduced to nitrogen dioxide by open copper, and the correct ionic reaction equation is: Cu+4H++2NO3 - Cu 2++2NO2 +2H2O, so D is wrong;

Therefore, choose b, 1, and in the following description of chemical reactions, the correct one is ( ).

A When 1 mol Na2O2 reacts with a sufficient amount of SO2, 1 mol of electrons is transferred

b Dissolve calcium carbonate in limescale with vinegar, which can be expressed as 2CH 3COOH + CACO 3 CA 2++2CH 3COO -+H 2O+CO2

c Laboratory-prepared SO2 gas, which can be reacted with dilute H2SO4 solution with Na2SO3 solution.

d cu and dismantling the feast on the thick hno 3 should be written as: cu + 4 hno 3 (thick) = cu 2 + + 2n o 3 +2no +2h 2o

Solution: a The essential characteristic of a chemical reaction is that new substances must be generated;

b. The essential characteristic of chemical reactions is that there must be new substances ready for the formation of vibrillin;

c. There is an energy change in the process of physical change;

d Chemical reactions must be accompanied by energy effects, which are generally embodied in the form of heat A chemical reactions are characterized by the formation of new substances, so a is correct;

b If a new substance is formed, there must have been a chemical change, so b is wrong;

c The process with energy change may be a physical change, so c is wrong; Sophora Hu.

d chemical reaction must be accompanied by energy effect, not necessarily heat is released, so d is wrong so choose a 3, the following statement about chemical reaction is correct ( ) a chemical reaction imitation is characterized by the formation of new substances.

b The formation of a new substance does not necessarily mean that a chemical change has occurred.

c A process with an energetic change must be accompanied by a chemical reaction.

d There must be heat released during the chemical reaction.

Problem solving ideas: a. Analyze and judge according to the energy change during the chemical reaction b. Analyze and judge according to the weaker metal activity of copper than iron c. Metathesis reaction is a reaction in which two compounds exchange components with each other to form two new compounds d. The ratio of the stoichiometric number of the product can be determined by the chemical equation of the electrolysis of water reaction a. Some chemical reactions are endothermic reactions, and some are exothermic reactions, so the option is wrong b. The metal activity of copper is weaker than that of iron, and it cannot react with iron sulfate solution. Therefore, the option statement is wrong c. Metathesis reaction is a reaction in which two compounds exchange components with each other to generate two new compounds, and the metathesis reaction is ,..

4. The following statement about chemical reactions is correct ( ).

a Chemical reactions are endothermic reactions.

b Copper can react with iron sulfate solution, and metallic iron is precipitated.

c In the metathesis reaction, the valency of the elements that make up each substance must change d In the electrolysis experiment, the ratio of the stoichiometric number of the product is: (h 2): o 2) = 2:1

Single selection c aThe displacement reaction ABCD must be a compound and may be elemental DIt is impossible to generate water, 2, c, and the displacement reaction reactants have elemental elements, and the equation for oxygen production in b is reversed.

D sodium hydroxide and copper sulfate reaction branch let the delay is not compliant, 2, for the chemical reaction a + b c + d the following statement is correct.

a.If one of the products c and d is elemental, then the change reaction must be a displacement reaction bIf A and B are two compounds, then C and D must also be compounds C

If the products c and d are two precipitates, then a and b may be salts and alkalis dIf A and B are salt and alkali respectively, then there must be a slippery species in C and D that is water.

Lab-made chlorine:

MnO2 + 4(H+)2(Cl-) = Heating = (Mn2+) Cl2 + 2H2O

The magnesium strips are burned in the air grinding brother's gas.

2mg + O2 = ignition = 2mgo

Plus town rent hot patina.

Cu2(OH)2CO3 = plus blind brigade fever = 2Cuo + H2O + CO2

A silver is solid and not ionized, so it does not react with reagents.

The metal activity (reducibility) of iron in B is less than that of zinc, so potassium nitrate and sodium chloride in C cannot be replaced, and it will not react to form water gas and difficult to ionize substances, so metathesis reaction does not occur. At the same time, since the ions can coexist with each other, no chemical reaction occurs.

barium sulfate precipitate is formed in d, so metadecomposition reaction can occur.

In view of your doubts, I would like to explain to you the definition of chemical reaction: the process of dividing molecules into atoms, ions, and rearranging atoms and ions to form new substances is called chemical reaction. Its essence is the process of breaking and re-aligning chemical bonds.

In the reaction, it is often accompanied by luminescence, heating, discoloration, and the formation of precipitates. The basis for determining whether a reaction is chemical is whether the reaction produces a new substance. According to the theory of chemical bonds, it can be judged whether a chemical reaction is based on whether there is the breaking of old bonds and the formation of new bonds in a change process.

To sum up, I think the answer is yet to be considered.

Hope it helps.

c ionization of k+ no3- na+ cl- these ions can coexist with each other (because the combination of two does not produce precipitation, gas and water) and therefore does not react.

A The activity of Bank of China is less than H+, so there is no replacement reaction, and the activity of Fe in B is less than Zn, so no reaction occurs.

Ba2+ and SO42- in D cannot coexist and the reacted BaSO4 is neither soluble in water nor soluble in acid, so the reaction occurs.

The one that can have a chemical reaction should be d

The answer is d, and the reaction produces a precipitate barium sulfate.