A little trouble with chemistry, a little problem with chemistry

The first one is incorrect, chemical changes are always accompanied by chemical reactions. In fact, chemical reactions are the process of gaining and losing electrons and bonding, which is accompanied by the process of releasing or absorbing energy, which is the object of chemical research, and nuclear reactions are listed separately.

The second is correct, which is the definition of a molecule, which is made up of atoms and is called a monoatomic molecule. The physical and chemical properties of a substance are all determined by molecules, so a molecule is the smallest particle that retains its chemical properties.

A molecule is the smallest particle that retains the chemical properties of a substance, and this sentence certainly applies to substances made up of molecules. If a substance is directly composed of atoms, then the atom is the smallest particle that retains its chemical properties.

The atoms contained in a molecule do not determine the chemical properties of the substance.

The first sentence is correct.

The first sentence is wrong, and electronics should also be considered.

The second sentence is true. The properties of matter are mainly determined by the structure of the substance itself, so the structure of the molecule is also one that determines the properties of matter.

Chemical changes and chemical reactions are different.

Chemical changes and chemical reactions are different;

The second sentence is correct;

Molecules are particles that maintain the chemical properties of a substance.

Chemical change is also called chemical reaction.

Atoms are the smallest particles in chemical change. --That's right.

A molecule is a type of particle that retains the properties of matter. --Incorrect (Change: A molecule is a particle that maintains the chemical properties of a substance).

Not true, but if you are new to the study of atoms, you should be able to understand that atoms are the smallest particles in chemical change.

1.By some definition, a compound in which all cations produced during ionization are hydrogen ions (H+) are called acids, and acids are covalent compounds. The melted state is not ionized.

If broadly speaking, it is the acid that can donate protons in the reaction. That may ionize in the molten state. For example, nahso4.

2.The weak electrolytes of alkalis are directly pyrolyzed when melted.

The strong electrolytes of the base are all directly ionized when melted.

Ionic compounds.

3.Salt is almost hardly insoluble. And the substance is more or less dissolved.

They are only in a state of melting, and they will not be electrolytically decomposed without any additional conditions.

4.There doesn't have to be a difference. It's special.

It is estimated that those salts are acidic salts, alkaline salts, so there are them.

For example, Ca(OH)2+NaHCO3==CaCO3 +NaOH+H2OCA(OH)2+2NaHCO3==CaCO3 +2H2O+Na2CO3.

1。Acids are covalent compounds and are not ionized in the molten state.

2。It is difficult to dissolve in water for weak alkalis, and is heated and decomposed into water and metal oxides3. Salts are ionized in the molten state regardless of their solubility, and insoluble salts do not necessarily decompose in the molten state, such as barium sulfate.

4。This needs to be analyzed on a case-by-case basis, and if there is too much alkali, it may be possible to further react, such as sodium hydroxide and aluminum chloride reaction.

First of all, you have to understand the difference between the three melts.

Melting: The physical process by which a temperature is higher than the melting point and a solid becomes a liquid.

Melting: The physical process by which the temperature is below freezing point and changes from a solid to a liquid.

Dissolution: The physical process by which a solid is dissolved into a liquid.

I watched it for a long time and didn't understand what "acid is melting" meant......

The title has already mentioned two metal oxides, what are the oxides of mg and zn? Isn't it MGO and ZNO? How could you possibly write znco2 and mg out?

The examination question, the question is about the generation of two metal oxides, and there are only two metal elements Zn and Mg on the question, so it must be Zno and MGO. Zn elemental liter 2 valence is oxidized, and combined with the requirement of the problem is to prepare CO, it must be C element is reduced, so the chemical equation is: MgCO3 + Zn = = MGO + Zno + Co

The experimental process questions are more comprehensive questions in the exam, and it is necessary to flexibly use the properties of common substances that you have learned, as well as basic reactions, redox reactions, and ionic reactions in aqueous solutions, and the ability to infer the structure and properties of unknown substances based on what you have learned. Of course, it is also necessary to practice the questions appropriately to accumulate test-taking skills.

1 The gas is generated in a liquid environment before the ascending sign is played.

2. Sodium bicarbonate and sodium carbonate are both strong bases and weak salts, which will be partially hydrolyzed in water to generate corresponding strong bases and weak acids. The degree of hydrolysis of sodium bicarbonate is greater than that of sodium carbonate, so the corresponding sodium carbonate solution is more alkaline.

3 In case of excess of hydroxide examples. Aluminum ions form aluminum hydroxide precipitation, and if hydroxide is still present, metaaluminate ions are generated;

4 ghost three that is also known as water glass, I think if the water volatilizes, it may stick the paper together, imagine that you know, the glue is dry;

5. I guess that the adsorption of silica gel is relatively strong, which is conducive to increasing the reaction area and so on;

6 Silver iodide is a small particle that acts as a condensation nucleus in the clouds, which you can understand with reference to the principle of artificial rainfall;

7. You should refer to the diagram of the experimental apparatus for the preparation of ammonia. I remember that the teacher talked about a few points at that time, 1 one is to prevent ammonia and air convection, adding cotton is easier to collect 2. In order to prevent ammonia from polluting the environment.

8. Concentrated sulfuric acid is extremely dehydrated, and the sucrose is carbonized;

9. The solution turns black because the reaction is violent and there are bubbles coming out of SO2, and the solution is equivalent to the copper oxide generated by stirring and is suspended in the solution because it has no time to react with sulfuric acid.

Related equation: Cu+H2SO4=CuO+H2O+SO2 Condition: Heating.

CuO+H2SO4=CuSO4+H2O (solution turns black to blue).

But if the sulfuric acid is sufficient, you end up with a blue solution

Give me a little more points, it's so hard.

1. There is gas on the left and right sides of the equation, and there is no rising arrow.

2. Because CO3 is less acidic than HCO3, it is more alkaline.

1。Principle, I don't fight in the first place.

The solution and the NaHCO3 solution are alkaline, alkaline, and the pH value is compared.

1.The first one turned out to have no gas so it had to be added, and the second one turned out to have gas as well.

2Na2CO3 is an alkaline (soda ash) sodium bicarbonate is an acid salt formed after the neutralization of strong alkali and weak acid, and it is weakly alkaline when dissolved in water. Salts are alkaline, acidic, and neutral.

The rest will not.

Not all of them can be merged at will, and there are many scenarios.

First of all, the side reactions that will cause them cannot be superimposed, that is, the reaction mechanism has changed.

Secondly, it is not possible to initiate the phase change, for example, the reaction that could have been reflected, such as bromine water, and the reaction with benzene as the reactant, will be extracted, and the reaction cannot be carried out.

Then, the reaction conditions are different, for example, one needs high temperature, one needs low temperature, for example, ethanol catalyzed by sulfuric acid, ethylene may be generated, ether may be generated, but the conditions are different, the difference in this reaction is exactly the temperature, 140, 170, two key points. So the conditions are determined, and these two certainly cannot be superimposed.

I don't think it's okay to add "any".

Because there are always exceptions, and it is always not necessary to be too absolute.

After some equations are combined, the substances that appear on the left and right sides can be deleted, so that the new equation may not have precipitation, gas or water formation, so it is not valid.

Of course, different conditions cannot be combined.