Chemistry problems, help! Help me! Chemistry

It is inferred that the physical properties of the metal are: small hardness, low melting point, less density than water, and silvery-white color.

Chemical properties: It can react with water to form gas (hydrogen).

Being able to cut with a knife means that the hardness is very small.

The heat generated by the reaction with water can melt the metal, indicating a low melting point.

Floating on the surface of the water indicates that the density is small, which is smaller than water.

The color is, of course, silvery-white, and the metal is generally silvery-white.

Exceptions, such as cu, do not react with water.

The chemical properties are.

It can react with water to form a gas, i.e., hydrogen.

For this kind of question, we can find a model, that is, NA as a sample to fill in the answer.

1 small (gently cut a small piece with a knife).

2 Low (reacts violently with water and melts into small white balls).

3 Small (floating on water).

4 Silvery-white.

It is easy to decompose when exposed to water, and heat is released, which can react with water to form gas (hydrogen).

1 Low hardness (a small piece is gently cut with a knife).

2 Low melting point (reacts violently with water and melts into white balls) 3 Low density (floats on the surface of water).

4 Silvery-white.

Chemical properties: It reacts with water and releases heat, which can react with water to form gas (hydrogen).

Small (hardness, oxidizes quickly in the air to form a dense oxide film).

Low. Less than water.

White. It can react with water to release gas (hydrogen).

2 ml (one flat finger); Cover the bottom of the tube.

2. a jar; medicine spoons; Paper.

1) Flat; Tweezers; Test tube mouth.

2) Lay flat; medicine spoons; Bottom.

3. Fine-mouthed bottles.

2) head-up; Burette; The lowest.

3) Dropper; Above; oblique placement; Reverse; Back.

4、；Paper. Left tray; Glass; Left; Right.

5. A (the amount to be weighed cannot be changed, and the left side indicates that there are more drugs) 6, D7, C (because the pallet balance can only be accurate.)

8. B (looking down means that the value seen is larger than the actual value, so the actual remaining amount is small) 9, C (the operation is incorrect, and the chemical experiment operation must be careful and meticulous) 10, (1) 10

2) Cleaning. 3) Insert the plug.

2 ml, cover the bottom of the tube with an Erlenmeyer flask medicine spoon.

1 All Answers: D Analysis: A It is obvious from the figure that the volume of hydrogen is greater than the volume of x, so A is wrong;

b In this system, the ambient temperature and pressure of the three gases are equal, so the larger the volume, the greater the amount of matter, so B is wrong;

For c and d, the amount of matter obtained by x just analyzed by b is greater than the amount of matter of y, and it is known from the question that the masses of x and y are equal, so the relative molecular mass of x is smaller than the relative molecular mass of y.

Unimpeded sliding means that the gas pressure is equal in 3 gears. Since the relationship between x, y, and h2 is not explained in the title, there are two ambiguous understandings here:

1) Even x and y will not be H2, because the relative molecular weight of H2 is the smallest, so if the mass is equal, its volume is the largest.

2) Even if x and y are not excluded as h2.

Overall, the conditions of the question are completely insufficient, and none of the four choices can be judged.

The second year of high school is far away from me, and I forgot what the specific chapter is about, the main difficulty of the nitrogen group is the oxidation and reduction of n, and the valence state during the period is more, and when writing the equation, pay attention to the valence state and the transfer of electrons. Rise and lose oxygen, and fall back. (Appreciation, loss of electrons, oxidation; The price is reduced, the electron is obtained, and it is restored.

The "student" is raised by the "teacher", and the "kindness" will come and "be repaid").

There is also a reaction that is similar to the disproportionation reaction. For example, in the reaction of ammonia and nitric acid, it is logical that the low valence state provides electrons, and the high valence state accepts electrons.

Take the properties of matter as common sense, gunpowder, Hou's alkali method, passivation, etc.

The most oxidation reaction of oxygen and fluorine is the strong electronegativity. There are several special reactions that can be regarded as strange things, such as the decomposition of hydrogen peroxide and the reaction of oxygen and fluorine.

One of the key points of the oxygen group is sulfur, which is the same method as nitric acid, in contrast.

I don't know if there's a chapter ahead of ionization equilibrium that I haven't talked about. Ionization mainly talks about electrolytes and non-electrolytes. Strong dielectrics are all ionized as ions, and weak electrolytes are very valuable for discussion.

Then there is ionization equilibrium, with an emphasis on the equilibrium constant, which is a natural rule that dictates a relationship between the concentrations of the various ions ionized by the non-ionized molecules of the weak electrolyte in the water in solution. For example, k=[h+][ac-] [hac], acetic acid, the concentration of each particle in the aqueous solution must comply with this formula, and the value is constant. A change in the concentration of one particle results in a change in the concentration of the other two.

Insoluble electrolytes are also an important focus. Insoluble but not completely ionized, most of the molecules dissolved in water will be ionized, so the insoluble electrolyte is also a strong dielectric. He has a solubility product ksp, which is very similar to the ionization constant above, taking barium sulfate as an example, the denominator should be [baso4], but since baso4 is a solid, the concentration is seen as if the concentration of sulfate in the solution is changed, such as adding sulfuric acid.

The concentration of Ba+ also decreases, resulting in a precipitate, which eventually makes the product of the two concentrations equal to Ksp.