The general law of various reactions in the first year of high school, don t come to the equation, g

There are many laws, but there is a common essence in them, and it is better to grasp this essence than to memorize them.

Strong acids make weak acids because the ionization degree of hydrogen ions is different, the binding force of acid radicals and hydrogen ions is different, who attracts hydrogen more strongly, and hydrogen ions with whom;

Difficult to volatilize and easy to volatile: for example, sulfuric acid to hydrochloric acid is because hydrochloric acid can be separated from the system of sulfuric acid, the reaction is easy to carry out, and the reaction tendency of hydrochloric acid is greater;

The formation of acid salts by multiple positive salts and multiple weak acids is also due to the binding force of acid ions and hydrogen ions.

To see whether a reaction can be carried out, it depends on who has more binding power with whom and whether there is a tendency to react. There is a theory of acid-base protons that you can look at. There is also an ionic reaction that can occur not only depends on the difficulty of ion binding, but also the specific situation of the system, such as refractory volatile and volatile.

First of all, you need to judge whether to react or not

Let's start with the most fundamental: chemistry is a science based on experiments, so if you do experiments directly and constantly change the experimental conditions, you can know that they are not reactionary.

If it's a question, then it can be like this.

Junior high school: Memorize the general properties of various substances and the special cases therein, and then make judgments accordingly. The common ones are the displacement and metathesis reactions of the four basic types of reactions, and the substitution reactions require that the elemental ratio before the reaction is more active than the generated elemental (e.g., the reaction of metals, acids, and salts); Metathesis reactions require precipitate, gas, or water in the product.

High school: I think in addition to experience, we should also know some judgment basis, and upgrade the requirements of the junior high school displacement reaction to the law of strength and weakness of redox reaction, that is, the oxidation and reduction of reactants should be stronger than that of products; It is necessary to upgrade the conditions of the metathesis reaction to the fact that there are substances in the product that will leave the solution (insoluble, volatile, difficult to ionize, etc.), so that the concentration of some ions of the reactants will decrease.

Of course, students who know that entropy change and enthalpy change know that whether the reaction can be carried out depends on whether δh-tδs (i.e., Gibbs free energy) is less than zero, and reactions less than zero can be spontaneous.

High school chemistry is very simple! Alas, let me tell you, after graduating from college, I can still recite all the elements in the periodic table The subgroup elements also have a basic understanding From alkali metals to halogens, we all know the properties and valencies of the halogen group, and I can understand at a glance what substances have what properties and what strong oxidizing properties I can see! Chemistry has to be memorized a lot, not rote memorization, it has to be integrated, and you have to know if you want to know no!

What double hydrolysis, what electrolytic reaction, as long as the high redox science is good, what is strong and what is weak, to the back, basically organic reactions, also need to know the principle of their reaction! Chemistry also mainly remembers the principle of reaction, and also can laxative! Although I studied automation control in college, I basically didn't forget those high school chemistry!

The first year of high school physics and chemistry really lays a good foundation, otherwise hehe! In the past, when I was studying, I scored a big score in physics and chemistry, and when I was a junior in physics, I scored 120 points, and we had a great score of 110 points, which was almost 40 points.

I'm a chemistry major, and I don't think I've heard of such a shortcut, but you can only follow the law of conservation of mass when writing chemical equations.

Acid (1) reacts with the indicator, the purple litmus test solution turns red when it is acid, and the colorless phenolphthalein test solution does not change color when it is acid.

2) Displacement reaction with active metal acid + metal == salt + hydrogen 2HCL Fe=FeCl2 H2

Alkali (1) reacts with the indicator, the purple litmus test solution turns blue when it encounters alkali, and the colorless phenolphthalein test solution turns red when it encounters alkali.

2) Reaction with acidic oxide alkali + acidic oxide - salt + water 2NaOH CO2 = Na2CO3 H2

Salt (1) Reaction with certain metals Salt + metal — new salt + new metal cuso4 fe feso4 cu

2) Reaction with acid Salt + Acid — New Salt + New Acid BaCl2 H2SO4 = BaSO4 2HCl

3) Reaction with certain bases Salt + salt — two new salts NaCl Agno3 = AgCl + Nano3

Strong acids produce weak acids, such as hydrochloric acid and calcium acetate, to produce calcium chloride and acetic acid. In the same way, the same is true for strong alkalis to make weak bases. And judging according to free energy, this is what you have to learn in the second year of high school. There is also the fact that the reaction always proceeds in the direction of generating precipitate.

Si O2 === High temperature) SiO2

2．si ＋ 2naoh ＋ h2o ＝ na2sio3 ＋ 2h2↑

3 Si 2Cl2 == High Temperature) SiCl4

4 SiCl4 2H2 === High temperature) Si 4HCl

5 SiO2 2C = = High Temperature) Si 2Co

6 SiO2 3C = = High Temperature) SiC 2Co

7 SiO2 cao=== high temperature) casio3

8．sio2 ＋ 2naoh ＝ na2sio3 ＋ h2o

9．sio2 ＋ 4hf＝ sif4↑＋2h2o

10 SiO2 Na2CO3 == High temperature) Na2SiO3 CO2

11 SiO2 CaCo3 === High Temperature) Casio3 Co2

12．na2sio3 ＋ 2hcl ＋ h2o ＝ h4sio4↓＋2nacl

2hcl ＝ h2sio3↓＋2nacl

14．h4sio4 ＝ h2sio3 ＋ h2o

15．na2sio3 ＋ co2 ＋ h2o ＝ h2sio3 ↓＋na2co3

A = B + C Replacement Reaction: Elemental A + Compound B = Elemental C + Compound D Metathesis Reaction: Two compounds exchange components, and there must be water or precipitate or gas in the product to react.

Conservation of charge Ah positron is equal to negative electron.

Some need to be memorized, most of them are regular, according to the type of reactant or generated, according to the reaction conditions, according to the type of reaction can be said to be the equation classification, so it is easier to remember, but it is impossible to master it all without spending a little effort.

Hmmm. First of all, the number of elements on both sides of the equation is the same, and the trim equation is to be checked. Also, well, when you come across an equation you've never seen before or forget about an equation, try to write about the more likely constituents.

The organic one is simpler, look at the place where the key is broken, and then connect to other organic matter