Senior 2 Chemistry Questions Explain the Reason Senior 1 Chemistry Questions Explain the reasons

Add koh solids.

Because when carbonate is dissolved in water, it will have an ionization reaction with water, i.e. CO3 2- +H2O = HCO3 - OH-

It's a reversible reaction.

When KOH is added, the extra OH- in the water causes the above reaction to move to the left.

Even if you get CO32- ionization becomes less.

This brings the sodium ion closer to the carbonate ion to 2:1

As long as the degree of CO32- hydrolysis is reduced, it can be close to 2:1

The hydrolysis of CO32- moves in reverse. Answer C

I only see that option A is water, and I can't see other options.

The sodium ion is twice as large as the carbonate ion, and the carbonate ion is hydrolyzed (can the equation be listed by yourself) into bicarbonate ions and carbonic acid, so the number of carbonate ions is reduced. The addition of water will promote hydrolysis and reduce the number of carbonate ions, and the sodium ions will not change, so it is not true. For the other options, you need to analyze its effect on the hydrolytic equilibrium.

There is an easy way to solve this problem, if you look at the alkaline solution of Na2CO3 because of hydrolysis, then you can add an alkaline solution to inhibit the hydrolysis, resulting in an increase in the number of carbonate ions, closer to 2:1).

Carbonate is a weak acid that can easily combine with hydrogen ions to produce bicarbonate ions and hydroxide ions after ionization in water.

Carbonate ion + water ==== bicarbonate ion and hydroxide ion.

So choose C and add KOH to make as many carbonate ions as possible.

Reason: The addition of potassium hydroxide introduces a large number of hydroxide ions, which inhibits the hydrolysis of carbonate ions.

Because Na2CO3 itself is 2:1, it is closer to the saturated state after adding Na2CO3 powder, and of course closer to 2:1

The answer should be b and c, the greater the concentration of salt solution in b, the smaller the degree of hydrolysis; The addition of potassium hydroxide in c inhibits the hydrolysis of salt!

C because the strong base weak acid is more dilute and hydrolyzed, but less than 2:1 The addition of Na2CO3 will increase the sodium ion at the same time The addition of KOH increases the hydroxide group to weaken the hydrolysis of Na2CO3, then the sodium ion is closer to 2:1 than the carbonate Heating will make it less than 2:

1, because hydrolysis is an endothermic reaction.

abc is the same periodic element, and it must be in the third period. 1)anabalccl

2)naoh

al2o3hcl

naoh+hcl=nacl+h20

al2o36hcl

2alcl3

An oxide of the element is a yellowish solid.

B is the stool cryptolead NA in sodium peroxide

A is oxygen. o

C12 mg

c is cl3(r+32)/(r+4)=

r=12 is carbon.

4. A can be regarded as sodium, B as magnesium, and C as aluminum.

Atomic radius. A is greater than B is greater than C

The metallicity of the element, a is greater than b and is greater than c

The degree of reaction with water is more than B and more than C

According to the order of nuclear charge number, A is smaller than B jujube is better than C

5。This element could be: Sulfur. k2scas

1.(1) A is the na element, B is the al element, and C is the cl element.

First, push A1mol elemental A to completely react with acid, which can replace 1GH2,That is, hydrogen, 2a h2, monovalent metal, cation with.

If Ne is the same, it is sodium, if there is more proton number in B, 2 more protons in B, it is Aluminum, and if there are 4 more protons in C than B, it is chlorine.

The chemical formulas of the hydrates corresponding to the most ** oxides of elements A and B are NaOH and Al(OH)3 The water-soluble first cilus of gaseous hydride of element C is called hydrochloric acid, and the ionic equation of the chemical reaction between the celery complexes in the above three types is OH-+AL(OH)3=ALO2-+2H2O.

oh-+h+=h2o

al(oh)3+3h+=al3++3h2o

c,1 gasoline and sodium chloride are immiscible with each other and can be separated; 2. The ethanol solution contains water and ethanol, and can be distilled with different boiling points; 3. Both sodium chloride and elemental bromine are soluble in water, but sodium chloride is insoluble in Ccl4 (carbon tetrachloride) or other organic solvents, while bromine is soluble in Ccl4 (carbon tetrachloride) or other organic solvents, so it can be extracted.

c. Gasoline and sodium chloride are immiscible with each other and can be separated by separating; Ethanol and water have different boiling points and can be separated by distillation; Br2 from sodium chloride can be extracted with CCL4.

Of the following substances, the one that cannot be called an anhydride is C

a、so2 b、sio2 c、no d、co2

Acid anhydride is the product of acid dehydration of H2O, you add H2O to each substance, and you get acid.

At the same temperature and pressure, the same amount of hydrogen and helium have the same b, da, atomic number b, volume c, neutron number d, and mass.

You won't be ?..

The following statement is true d

A. The dilute solution must be an unsaturated solution B. Normally, the solubility of CO2 in water is greater than NH3 C. Add a small amount of KNO3 solid to the NaCl saturated solution, and KNO3 will not dissolve D. Increasing the temperature does not necessarily make the saturated solution become an unsaturated solution.

Remember this chemistry problem.

I think C

Because anhydride is the product of acid dehydration, SO2 in A corresponds to H2SO3, SiO2 in B has H2SiO3, CO2 in D corresponds to H2CO3, so only C is not anhydride.

C, A is the anhydride of sulfurous acid, B is the anhydride of silicic acid, D is the anhydride of carbonic acid, and nitric anhydride is N2O5

1. At the same temperature and pressure, the number of molecules of hydrogen and helium is the same. Hydrogen has two atoms in one molecule while helium has only one and hence the number of atoms is different, there are no neutrons inside the hydrogen atom so c is also not true, h2 is 2g mol and he is 4g mol so d is also not true. Only the volume is the same in the case of the same temperature and pressure of the substance, so B is chosen

2. A is incorrect, because for example, calcium hydroxide, the solubility in the saturated state is only about grams, which must be a dilute solution;

b is incorrect, CO2 is about 1:1, NH3 is 1:700, obviously NH3 has a large solubility.

c is incorrect, saturated solution is only saturated with one ion in it, so it can still be dissolved after adding kno3.

d is correct, because the solubility of some substances decreases with temperature.

3. A contains oxygen atoms.

The CO2 in b has a total of atoms.

The water in c is , for the total atoms.

10gne in d is a total atom.

Therefore, I chose C (I just chose the wrong one).

Supplement: The detailed calculation process of the third question:

Option a is to multiply by 2 atoms, vested.

Option b The volume of 1mol of gas in the standard case is liters, option b is liters, and then the same calculation as option a, is.

Option c Liquid divided by density to get the amount of water converted into matter as Total Atoms as.

Option d The atomic weight of the Ne is 20, and the Quantity of the Substance of 10gNe is the Monoatomic Molecule, so the Quantity of the Substance is.

1.Option B At the same temperature and pressure, the molar volume of the gas is the same, hydrogen and helium, one is a diatomic molecule, one is a monoatomic molecule, one has neutrons, one does not, one is 2g mol, and the other is 4g mol

2.Option D: The solubility of calcium hydroxide solution decreases with the increase of temperature The dilution and concentration of the solution refer to the amount of solute contained in a certain amount of solution, and it doesn't matter whether it is a saturated solution or not, the solubility of NH3 is higher than that of CO2, and Kno3 will dissolve, unless NaCl is added

3.Option d A is a diatomic molecule, option b is a polyatomic molecule, and option c means that the water swim option d is a monoatomic molecule 10 10 = 1mol

(1) b, the same temperature and pressure of the same mass and the same volume;

2) d, e.g. ca(oh)2;

3) C, H2O is a liquid, 40C density is about 1g ml, for, the mass of matter, the number of atoms, the maximum.

b If you can do this ...

Prove that you have learned about the hydrolysis of salt...

NaHCO3 before hydrolysis:

c(na+)=c(hCO3-) c(h+)=c(OH-) can be obtained according to the conservation of charge in solution).

Because HCO3- in NAHCO3 is a weak acid group...

It will be hydrolyzed, while H20 ionizes H+ and OH-

HCO3- binds to H+ in H20 to form H2CO3, so HCO3- decreases...

And NA+ does not change ...

oh - Relatively speaking, it has increased ...

So choose B

alkaline solution, so the concentration of hydroxide ions is greater than that of hydrogen ions.

The concentration of sodium ions is the largest, choose b

Do you understand?

The hydrolysis of HCO3- is mainly considered.

Due to the presence of hydrolysis, HCO3- is consumed, so C(Na+) > C(HCO3-) while hydrolysis consumes H+, making C(H+).

Answer: B

Reason: NaHCO3 solution is an alkaline solution, so C(H+)C(Na+) C(HCO3-) Note: There are only four ions in the solution.

The answer is b

Reason: The salt is a strong alkali and weak salt, and the solution is alkaline, so C and D are incorrect; HCO3- hydrolyzes and ionizes, so A is incorrect and B is correct.

Increasing the pressure The direction of the reaction (chemical equilibrium) moves to the side with less gas, and the increase in the conversion rate of A indicates that the chemical equilibrium moves to the right, so A must be a gas and C must not be a gas. The chemical equilibrium of the lower temperature shifts in the direction of exothermic so that the reaction is exothermic.

Remember the conclusion (self-summarized): increase the pressure and the chemical equilibrium moves towards the side with less gas;

The pressure is reduced, and the chemical equilibrium shifts to the side with more gas.

As the temperature increases, the chemical equilibrium shifts in the direction of endothermy;

The chemical equilibrium of the lower temperature shifts in the direction of exothermy.

So the answer is a

a's conversion rate increases" can be rolled out to the balance of the right shift. Increasing the pressure and moving the equilibrium in the direction of the decrease in the number of gas molecules, indicating that the reaction is decreasing in the number of gas molecules to the right, so A must be a gas and C cannot be a gas. Lowering the temperature and shifting the equilibrium in the direction of exothermic means that this reaction is exothermic to the right.

So the answer is a

If the pressure increases and the conversion rate increases, then no matter what state C is, A must be gaseous.

Lowering the temperature indicates that the positive reaction is exothermic.

Increasing the pressure strengthens the chemical equilibrium in the direction of decreasing the volume of the gas, and lowering the temperature chemical equilibrium shifts in the direction of the exothermic positive reaction, so the answer should be a(People in the rivers and lakes).

A: Yes, but in addition to the conversion into heat energy, there is also light energy. The options are incomplete, but correct.

b: False, based on CXHY + x+ == xCO2 + H2O and the relative atomic masses of carbon and hydrogen. When a hydrocarbon of the same mass is burned, the amount of oxygen consumed is directly proportional to y x.

This is the law of organic chemistry in the first year of high school.

C: False. According to the principle of chemical reaction learned in the second year of high school, it can be known that generally speaking, the higher the energy of the substance, the more unstable it is.

D: False, the heat of reaction is at 101kPa and 25 measured values, and the water is liquid at this time. i.e. 4H2O(L).

In summary; a Correct.

I did it with elimination. BCD: I'm sure it's all wrong.

B Yes, A also has light energy, and C isobutane has a low heat of combustion, so the more stable D water state should be in a liquid state.

A, right, because it's mostly heat.

B, wrong, the same mass of propane combustion produces more heat.

c, false, n-butane combustion releases more heat, which means that the energy is high, and the higher the energy, the more unstable d, false, the water produced by the combustion heat is liquid.