Senior One Chemistry Questions, thank you for the guidance, Senior One Chemistry Questions, thank yo

Number of molecules: The number of molecules.

Number of particles: The number of molecules, atoms, and ions.

n=n na na is Avogadro's constant, which is a fixed value (so the ratio of the quantity of matter is the ratio of the number of molecules).

n represents the amount of matter, n represents the number of particles, and matter is composed of molecules, so when we talk about a certain substance, we are talking about the ratio of the number of molecules.

For example, in NaCl solution, the particles present are: sodium ions, chloride ions, and water molecules.

If it's a molecule, it's only a water molecule.

This is the difference between a particle and a molecule.

Hope you get the idea.

The number of molecules is the number of molecules......Particles cover molecules, atoms, and many more. Because the number of molecules = n*na, because na is a constant, the ratio of the quantity of matter is the ratio of the number of molecules. N, n, v, etc. are just a symbol, but in order not to cause ambiguity, everyone conventionally uses a certain letter to represent a certain meaning, such as n represents the amount of matter, v represents volume, etc., but in fact, as long as it is stated in advance and does not cause ambiguity, it is okay to replace it with any symbol.

As for the number of particles = the number of molecules, it is definitely wrong, and it is said above that the concept of particles includes molecules, atoms, and so on. The two are the same only when it is determined that the particles in the problem are specific molecules.

Particles include various particles such as molecules, atoms, ions, etc., therefore, the number of molecules is not equal to the number of particles.

The answer is d because the average relative molecular mass of air is 29 and the molar mass of matter is numerically equal to its relative atomic mass or relative molecular mass, so the density of the gas is also proportional to its relative molecular mass, because only hydrogen has a smaller relative molecular mass than air, that is, less dense than air, so it sinks in hydrogen.

d The molar mass of hydrogen is smaller than that of air, so the density is smaller than that of air, and the balloon that can move in the air contains the same gas density as air, so its density is greater than that of hydrogen, so it will sink.

The answer is d hydrogen. Standing still in the air indicates that the molecular weight of the gas in the balloon is equal to about 29 in the air, and the molecular weight of the balloon is greater than 29, that is, the density is greater than the gas in the balloon!! Only hydrogen is less dense than the gas inside the balloon!

dHydrogen is related to the density of the gas as described in the rain, molar mass.

Then, the molar mass of air is generally 29

Oxygen 32 chlorine 70

CO2 44 Hydrogen 2

The relative molecular mass of methane is 16 and that of oxygen is 32

So the amount of methane at the same mass is twice as large as that of oxygen.

That is, the ratio of methane to oxygen volume is two to one under standard conditions.

Wow, on the first floor, are you that an isotope)

Methane CH4 has a molecular weight of 18, oxygen O2 has a molecular weight of 36, and the molecular weight ratio is 1:2

Because the volume of gas with the same amount of substance is the same under standard conditions, the ratio of volumes is 2:1 at the same mass

The molecular weight of methane CH4 is 16, the molecular weight of oxygen O2 is 32, the molecular weight ratio is 1:2, and the mass is Xn(CH4)=X 16, N(O2)=X32V(CH)=N(CH4)*VM=(X*VM), 16 V(O2)=N(O2)*VM=(X*VM) 32

So v(ch):v(o2)=(x*vm) 16 :(x*vm) 32=2:1

1.Sodium is very expensive, and the size of soybeans can be clearly observed.

2 light blue flame, easy **, it seems that there is no special test of hydrogen experiment 3, burning, the flame is yellow, this is the method of checking sodium, just use litmus reagent to check the acidity and alkalinity.

4. There is gas coming out, producing blue precipitate.

2na+2h2o=2naoh+h2

2NaOH + CuSO4 = Cu(OH)2 + Na2SO45 loses its metallic luster and generates a white powder, which is deliquescent to form a white massive solidSodium is placed in the air to form sodium oxide->sodium hydroxide->sodium carbonate.

6. Generate light yellow solid, sodium is heated in the air to generate sodium peroxide, 7. Sodium oxide reacts with water, and the solid dissolves without other phenomena, and reacts with carbon dioxide to form a white lumpy solid, and there is no obvious phenomenon with hydrochloric acid to react with the solid dissolution without other phenomena.

Too much to be impatient, so be it.

The reaction is violent. Too much sodium can be dangerous.

The reaction is violent. Too much sodium can be dangerous.

Light up to see the color.

2na+cuso4=cu+na2so4

1: Sodium is too large and exothermic and will burn on the surface of the water, (I have seen it), and it is dangerous to do experiments.

2: Ignite, cover with a beaker with water droplets, add clarified lime water, do not mix. 3：

Cu + 2H2SO4 (concentrated) = Heating = CuSo4 + SO2 + 2H2O

Each 1molCu reaction consumes SO42-1mol to produce CuSO4 1mol.

After the reaction, the number of so42- is , before the reaction, so the so42- is consumed, so cuso4 is, so the amount of copper sulfate in the solution is concentration.

Originally, the amount of concentrated sulfuric acid was, and later became, so the lost sulfur element (SO2) is, then the copper participating in the reaction is, so the copper sulfate concentration is.

Let the mass of the water reacted be x g

2na + 2h2o ===2naoh +h223x)/18 x (20x)/9

Because the solution produced by the reaction is just saturated at 10, there is.

20x)/9]/(

The solution is x=so the mass of sodium metal is.

There may be a bit of a calculation problem.

The mass of the solution m1 = x + let the mass of sodium be x).

NaOH mass m2 = x 23 * 40

m2/m1=25/(25+100)

Count the rest.

Element B already has an M layer electron to prove that the L layer electrons are full, so A+B=8, so neither A nor B can be greater than 8, the same as element B, because there is another layer of electrons outside the subouter shell, so the subouter shell of element A is also full of electrons, but B is less than 8, so the subouter shell of element A should be the K layer, so B=2, so A=6, so element A is element O, element B is element Si, so the compound is silicon dioxide, and the chemical formula SiO2.

The number of electrons in the m shell of element b (a-b), - indicates that a>b, so, this outer shell b=2b has l layers, there must be 8, so a=6

i.e. a is 2,6, i.e. o

b is 2,8,4, i.e. si

i.e. siO2

a+b=8, a is greater than b to have the number of electrons in the m shell of element b.

According to "the outermost electron number of element a is a, and the number of secondary outer electrons is b", it can be determined that b = 2, then a = 6

That is, element A is oxygen, element B is silicon, and the compound formed is SiO2

Al3+ has 3 positive charges, Mg2+ has 2 positive charges, the whole solution is electrically neutral, and the ratio of the amount of Al3+ and Mg2+ (ions) is 2:3 to infer that the positive charges shared by these two ions are equal. The sulfate ions in the 2molSO4 ion mixture have a negative charge of 4 mol, so half of the 2mol charge of the cation is carried by magnesium ions, so the magnesium sulfate is one mole, so the mass of magnesium sulfate is··· Do the math yourself!

Let the amount of Al3+ be 2a, then the amount of Mg2+ is 3a.

Because the solution is electrically neutral.

So: 2a 3+3a 2=2mol 2 solution: a=1 3mol

So: m(mg2+)=3 a 24g mol=24g

First of all, thank you for opening the sedan car!

1. "a, b, c, d, e are the first 20 elements, and the atomic number increases in turn, b, c, d, the same period" indicates that b, c, d are the elements in the second period;

2. "E and other elements are not in the same period", which means that the fourth cycle (potassium and calcium are two possibilities) 3. "The hydrates of the most ** oxides of B, C and D can react with each other" B and C hydroxides can react, which means that there must be amphoteric hydroxides in B and C, that is, Al, and because "the atomic number increases sequentially", therefore, C is Al, and only sodium hydroxide reacts with the hydroxide of C, so that B is Na; C and D, state sum and B and D can react, then D is acidic, in the pre-occlusion such as element 20 and the atomic number is less than Al, there is only S, and its chemical H2S can react with B and C, so we know B, Na

c，al d，s

4. "A and D are the same main family" then A is O

5. "E and other elements are neither in the same period nor in the same main group" can indicate that E is calcium.

The answers to fill in the blanks below will not be explained!