2014 Chemistry Contest Help, 2012 Chemistry Contest Preliminary Round Questions

It is recommended that the landlord first study carefully in class, gnaw through the knowledge of high school, take the synchronous competition tutoring book, participate in the school's competition training, and then communicate with the teacher more. At the end of the first year of high school or the beginning of the second year of high school, you should start to gnaw on the university textbooks, from inorganic to organic to analytical chemistry to physical chemistry to advanced inorganic chemistry, you have to read carefully, and the first two books are the key points. Inorganic Chemistry is recommended by the three schools to co-edit the fourth edition of Inorganic Chemistry, organic recommendation Xing Qiyi "Basic Organic Chemistry", analytical chemistry recommendation "Analytical Chemistry" of Wuhan University, physical chemistry can not be recommended, tragedy.

Advanced Inorganic Chemistry Recommended by Southern Normal University "Concise Course of Advanced Inorganic Chemistry". Then it's about doing questions, reading books repeatedly, doing questions, reading books repeatedly, and asking the high school teacher to be confused. The chemistry competition is based on reading university books, work hard, I was in Jiangsu Province in 2009, and the above is experience.

I doubt that the first floor is not from a chemistry class I don't really learn chemistry well will tell you that it is as simple as memorization I suggest that the landlord should lay a good foundation first and deeply understand the principles of chemistry If you think there is basically no problem in the book You can buy a book on chemistry competitions You can buy a thinner and simpler book later Then it should be more effective .

I think chemistry is about memorizing more knowledge points, memorizing the conditions of chemical reactions, phenomena, and chemical equations, just like biology.

You need to be interested in chemistry first. Then you will have the patience and the confidence to learn. Huajing's road is very hard, you still have a teacher to teach, and I am also a freshman in high school.

I've always learned by myself, and I don't know how to ask more questions. Laying a good foundation and reading more books is definitely better than doing questions, when you go out for training. You have to take good notes, read them at night, and then ask the teacher the next day.

If you have any questions, go to the chemistry bar and discuss them, buy a few chemistry contests to read, and don't think of the contest as a tool to send them away. If you blindly study chemistry for the sake of pursuing the guarantee, then you will never be able to stick to it, come on. I have time to add my QQ and communicate with me to 867481838

Let's talk about my personal opinion:

First of all, about entropy change. As a result of the beating, the atoms inside Cu(a) must have been ectopid, resulting in a more or less altered arrangement of unit cells. Macro realization is the deformation of the appearance of the copper plate. As a result, the arrangement of the atoms increases in chaos and the entropy increases.

About enthalpy change. Since it is solid, there is definitely no need to consider the expansion work. In addition, just hammering does not change the metal bonds of the copper plate (which is well explained by the electron gas theory), so the heat of the copper plate becomes zero (there is a change in heat that is also converted by mechanical work, and has nothing to do with the copper plate itself).

According to h= u+p v, the enthalpy becomes 0.

Personal opinion, please bear with me if there are mistakes

218g - is the sum of the mass of magnesium sulfate, zinc sulfate and ferrous sulfate produced.

50g – is the sum of the masses of a mixture of magnesium, zinc and iron.

So 218-50 = 168g (this is the sum of the mass of pure dust magnesium sulfate, zinc sulfate and ferrous sulfate in the celery thry).

In H2SO4 the sulfate is 168g, and the mass of sulfuric acid = 168 98 96 = the mass of hydrogen can be set to x

98x = grams.

1.Schedule:

According to the different provinces, it is generally the preliminary competition in the city, then the primary selection in the province, and then the preliminary round of the national high school chemistry competition, and then the provincial team selection after passing the national final, and then the winter camp;

2.Total Score:

The full score is 100 points, and as far as the beginning of the country is concerned, the score line varies from province to province.

Generally, it takes 70 to 80 points to save one.

3.Benefits::

If it is a provincial one, you can obtain the qualification of escort and take the college escort examination in the third year of high school.

From the next session to cancel the qualification of the escort, there should be a preferential policy for the college entrance examination;

4.Knowledge:

If you want to achieve that achievement, you must carefully study the inorganic and organic children several times, and properly look at some analytical chemistry and structural chemistry.

High school knowledge alone is certainly not enough;

B NACL should be chosen

In solution, both the strong electrolytes Na3 and KCl are completely dissociated into ions. There are only H2O and Na+, No3-, K+, Cl- in solution. When heating and evaporating the crystals, it is only necessary to see which of the salts composed of these four ions has the least solubility at higher temperatures; The least soluble salts are precipitated first.

NaCl is relatively speaking, the one with the smallest solubility at high temperature should be him.

I remember that the solubility of the four salts was the lowest among the four salts at room temperature, so the first to precipitate was kno3.