Whoever is good at chemistry in the ninth grade, tell me about it

I'm a good learner, I can tell the landlord about it.

Interest is the best teacher, if you are interested in chemistry, it is the best thing, once you have an interest, you will study chemistry without sleep and food, obsessed with doing experiments and chemical research, and you may chase higher goals such as chemistry in high school, which is the case with me.

If you are not already interested, you can cultivate it through the following methods:

1. Ask to go to the school laboratory and do experiments seriously, you will find the fun of experimental chemistry and fall in love with chemistry.

2, search for some chemicals of interest in the encyclopedia, the above is generally very comprehensive, if you find that there is no in the process of checking one, continue to search with the encyclopedia, and so on, you will find that you were going to learn a thing, but in the end you learned a bunch, happiness will enrich yourself, this is the way to further cultivate interest.

3. When you feel that you are already very interested in chemistry, go and buy a book "Inorganic Chemistry", a very good book, divided into two volumes, which can be bought in Beijing Xinhua Bookstore, it can almost all your questions in junior high school and even high school, at this time, it is not used for experiments, no need to go online, a book can lead you to success.

This is my personal experience, and I don't want to thank you, but I want to thank you in advance.

Chemistry is a liberal arts, not to a certain extent, memorizing more knowledge points, practicing more, just learning a solid point.

Is 9th grade the third year of junior high school? Chemistry still has to memorize, remember the properties of ion groups, memorize experimental operations, memorize reaction phenomena, and mainly do more memorized.

Basic knowledge is very important After mastering the basic knowledge, focus on the key points and do the questions, and finally do the questions by question type Special training is very important.

In understanding the process of material change: chemical change, physical change definition; Classification and definition of substances: pure substances, mixtures; Definition of Classification of Pure Substances:

elemental, compound; the name (including common name) and writing of the chemical formula; Relative atomic mass, relative molecular mass, calculation of valency of each element in the chemical formula, calculation of the mass fraction of each element in the molecule, ratio of the number of atoms in the molecule, mass ratio of each element, calculation of the mass fraction of an element, writing of chemical equations and related calculations and other basic definitions. Understand the physical and chemical properties of each substance, the preparation method (laboratory, industry), and the use in daily life; Precautions for the three phases of each experiment: before, during, and after each experiment. A deep understanding of chemistry is a science that always pays attention to the prevention and control of environmental pollution.

If you can memorize the above definitions, principles and subtle knowledge points of related substances, it is still very easy to score 100 points and get 80+. The main thing to remember is that if you are afraid of getting tired, then give up quickly and find a master to learn a skill, no one can succeed without hard work, and behind genius is often a cruel world that few people know.

The conclusion is that "the one that becomes turbid is carbon dioxide", and the presence of gas in carbon dioxide that makes clarified lime water turbid" describes the chemical properties of carbon dioxide.

The conclusion of this kind of experiment is based on the purpose of the experiment, for example, it is mentioned in this question that the purpose of the experiment is "an experiment to distinguish between carbon dioxide and gas", so the conclusion is the result of the difference between gases, not the properties of gases.

Carbon dioxide is the gas that makes lime water cloudy.

Oxygen is a combustible gas that can rekindle sparkled sticks.

The subject you are talking about is two different bottles of gas, so this is your first understanding.

co2+ca(oh)2==caco3↓+h2o

2co2+ca(oh)2==ca(hco3)2

Carbon dioxide itself makes lime water turbid.

--- owner Look here---

One experiment is "CO2 is unknown, we need to test which is CO2".

Another experiment "Carbon dioxide is known, and we need to study the properties of carbon dioxide".

The one that has become turbid is carbon dioxide", apparently saying that the test is not known, and the carbon dioxide is unknown "The carbon dioxide contains the presence of gases that make the clarified lime water turbid", apparently saying that the research and carbon dioxide are known.

Carbon dioxide + lime water (Ca(OH)2) = calcium carbonate.

The concentration of 200 grams of light brine is 1%, indicating that the solid brine mass of sodium chloride = 1%, so the solid weight of sodium chloride is 200 * 1% = 2 grams, and the amount of water added is 200-2 = 198 grams.

This metal element symbol is denoted by r and its relative atomic mass by x 2r + o2 === 2ro

2x --2x+32---4

2x)/ = (2x+32)/4

Solution: x = 64

Let the relative molecular mass be x, then a+o2==ao

x x+16

4g column formula x (x+16)=, the solution is x=64

The answer is seen in Sui Chi's picture below, guessing that Richard Ran did not.