Chemistry problems are for specific analysis, and chemistry problems are for detailed solutions.

The landlord is 98 years old.,It's probably a year of high school.,So you must have learned the "amount of matter".

Altogether, dissolved in 2mol HCl, since it is not stated that it is completely soluble in HCl, it is impossible to judge whether hydrochloric acid is left:

The reaction equation is:

Mg + 2HCl == MgCl2 + H2 2AL + 6HCl == 2ALCL3 + 3H2 2NAn + 2HCl == 2NaCl + H2 2NA2O == 2NaOH + H2 MgCl2 + 2NaOH == MG(OH)2 +2NaClALCl3 +3NaOH == AL(OH)3 +3NaClWe can find the transformation process of each substance from the above equations.

mg→ mgcl2→ mg(oh)2

al→alcl3→al(oh)3

na→naoh→nacl

We can find that in the end, all the Cl elements in the original HCL are converted into NaCl, and a Cl element corresponds to an OH-, so when all the Cl elements are converted into NaCl, the elements also happen to be completely precipitated, that is, the mass of the Na element in the final generated NaCl is the mass of the added Na, and the Cl element is all from HCl, that is, N(NaCl)=N(HCl)=2mol, M(Na)=2 23=46G

That is, 46g of sodium metal needs to be added.

If you don't understand, please ask, thank you.

Analyse. The mixture does not know the proportion, and when it reacts with 2mol HCl, there may also be HCL remaining, and there may also be AL,Mg remaining, it is noted that Al(OH)3 can react with both acid and base, and NA is added to produce OH- The by-product is H2. In order to maximize the precipitation after the reaction, therefore:

After the reaction, all Mg,Al exist as metal hydroxides, and there is no excess HCl. There is no excess NAOH, otherwise, the precipitate will dissolve. In this way, the element Cl or Na can only exist in the form of NaCl salts

X Al(OH)3 + Y mg(OH)2 + 2HCl+ infinite H2O The product cannot contain any other substances.

Therefore, the addition of NA can only be 2mol 46 grams.

1000ml, 2mol l hydrochloric acid in the amount of HCl substance 1L * 2mol l 2mol

mg+2hcl=h2↑+mgcl2 mgcl2+2naoh=mg(oh)2↓+2nacl → hcl～naoh

2al+6hcl=3h2↑+2alcl3 alcl3+3naoh=al(oh)3↓+3nacl → hcl～naoh

2na+2h2o=2naoh+h2 naoh In short, there is a relation:

hcl～naoh ～ na

1mol 23g

2mol x

x＝46g

Mg-24 and Al-27 bind anions twice and three times as well. The amount of precipitation is stronger than that of magnesium.

Altogether, dissolved in 2mol HCl, magnesium. When the mixed aluminum powder is elemental:

Aluminum binds anions.

Magnesium binds anions.

It has been calculated that hydrochloric acid is surplus in any case.

To paraphrase the upstairs paragraph;

To maximize the amount of precipitation: the precipitate can only be aluminum hydroxide, and sodium metaaluminate cannot be generated, so Na exists in the form of sodium chloride, N(Na)=N(Cl)=2mol, M(Na)=46 grams.

The precipitate is magnesium hydroxide aluminum hydroxide, if the precipitation amount is the largest, sodium metaaluminate cannot be generated, so Na exists in the form of sodium chloride, n (Na) = n (Cl) = 2mol, M (Na) = 46 grams.

Discussion 1: In order to calculate the friend-virtual mass fraction of magnesium, one of the other data that needs to be measured in this experiment is the mass of the powder after combustion.

Discussion 2: If the experiment is carried out with air instead of O2, the measurement results (Yes. (Fill in 'Yes' or 'None') impact.

The second group did not consider the following experimental scheme: the BG magnesium-aluminum alloy was weighed and completely reacted with a sufficient amount of dilute hydrochloric acid.

In order to calculate the mass fraction of magnesium, one of the other data that needs to be measured in this experiment is (the reaction is higher than the volume of hydrogen gas.

Solution: Suppose the volume of O2 is V liters (the amount of matter n=V, then the volume of Nuo2 is 4V liters (the amount of matter is n=V, and the volume of the whole flask is 5V liters.

The reaction equation: O2 + 4NO2 + 2H2O

4Hno3 Because O2 and No2 react completely, 4*V molhnO3 is generated

Because the solution volume is 5 v liters.

So the solution concentration c = (4*v

If you have any questions, please feel free to ask.

Answer: Hydrogen fluoride is a liquid under the BA standard condition!

c As the reaction proceeds, the concentrated sulfuric acid becomes diluted, and the two no longer react.

The ammonia synthesis reaction is a reversible reaction, and the reactants cannot be completely converted into products!

A: Under standard conditions, hydrogen fluoride is a gas, and hydrofluoric acid is considered to be a liquid, so option A is not wrong.

B: It should be changed to the standard condition to be correct, although it is a mixture of gases, we found that the experimental formulas of C2H4 and C3H8 are both CH2, so it can be found as 1Na

C: As the concentration decreases, the reaction will end, so it will be less than D: This reaction is reversible and cannot be carried out in one direction.

To sum up: choose A

A right. The proportion cannot be determined in B, and the result cannot be found in C, and when the concentrated sulfuric acid reaction becomes dilute sulfuric acid, D will stop as a reversible reaction.

How can Qiong Yao's books be bought.

As can be seen from the figure, the amount of H2 produced is equal. A is correct, compared with 10% sulfuric acid and 20% hydrochloric acid, the H+ concentration of hydrochloric acid is larger, and A puts 10% B sulfuric acid into the mass.

The amount fraction is 20% dilute hydrochloric acid. It takes a short time to produce H2 of equal mass, A, so the metal activity A>B, B is correct.

There are two metals of equal mass, if they are reacted in a sufficient amount of acid, the reaction with a small molar mass produces more H2, due to the same H2 generated.

Many, so one metal is left (with a small molar mass), and the other is just the reaction or also leftover, and the acid is all reacted. Therefore, there must be all metals.

The remaining statements are incorrect.

The ratio of the amount of solute in the dilute sulfuric acid consumed to hydrochloric acid must be: if the ratio of the amount of the substance is, 1:2; If the mass ratio is: 98:73

Therefore d is incorrect.

Answer CD

c From the image, we can see that a is correct, what does the former and the latter refer to? If the former refers to A and the latter refers to B, then A has a shorter reaction time than B and A is more lively than B.

If this is not the meaning, because the concentration and type of acid are different, it cannot be compared, option b is also wrong, the mass of the two metals is the same, if the amount of acid is sufficient, the hydrogen produced must be different, and the quality of hydrogen produced now is the same, indicating that the metal must have the same surplus, it is not sure whether both are left, and the mass of the two acids is not given, it is impossible to judge.

To produce the same mass of hydrogen, the ratio of the amount of sulfuric acid consumed to hydrochloric acid is 1:2

The wrong one should be C, AD can be sure to be correct in the first place, and as for C to say that all the acid is consumed, it is uncertain.

Steelmaking plants produce CuSO4 from SO2-containing exhaust gas. In production, exhaust gas is introduced into the CuSO4 solution mixed with CuO powder, and the reaction is: 2CuO+2SO2

o2====2cuso4。To prepare a CuSO4 solution with a solute mass fraction of 20%. Use a sufficient amount of cuo powder and 5000g of 5% cuso4

Solution to dispose of exhaust gases. If G SO2 is present in each litre of exhaust gas, and the SO2 is completely absorbed, how many litres of exhaust gas can be treated? 5000g*5%+x=(5000g+x)*20%x= 128 320 y Each liter of exhaust gas contains g SO2, and the SO2 is completely absorbed, and 375 liters of exhaust gas can be treated.

Analysis: After the second part was heated with a sufficient amount of NaOH solution, gas was collected, which indicated that the solution must contain NH4.

After adding a sufficient amount of barium chloride solution to the third part, the precipitate grams are dried, and after washing and drying with sufficient hydrochloric acid, the precipitate mass is grams, and the final precipitate is barium sulfate, indicating that the original solution contains sulfate ions.

g precipitated as a mixture of barium sulfate and barium carbonate, N(BaCO3) which indicates that 100 ml of solution contains carbonate ions.

The first addition of silver nitrate solution produces a precipitate, which may be silver carbonate or silver chloride, so chloride ions are possible ions.

Due to the presence of sulfate ions, barium ions must be absent. Magnesium ions must be absent due to the presence of carbonate ions.

According to the principle that the solution is not charged, it can be seen that potassium ions must be present.

To sum up: there must be: potassium ions, ammonium ions, carbonate ions, sulfate ions

There must be none: magnesium ions, barium ions.

There may be: chloride ions.

There is NH4+ because it can react with NaOH to produce gas. There are SO42- and CO32-, which are not completely dissolved in hydrochloric acid because of the precipitate produced by Ba2+. There must be no Mg2+ and Ba2+ because there is CO32-

There may be k+, cl-

This has similarities with some of the laws of oxides.

PBS, SNS is similar to CO, CO is a non-salt oxide, then SNS is a non-salt sulfide (by analogy with the properties of the main group).

SNS2 OK.

Bi2S3 is not good, the five main families need to reach the most**.

Hope it helps!

Seawater is a huge treasure trove of resources, and the following statement is true: A iodine element, also known as the "marine element", is correct.

b Magnesium is the most abundant metallic element in seawater.

Wrong, apparently it's the most na.

c The process of extracting salt and iodine from seawater is a physical change, iodine exists in the form of ions in seawater, and the extraction is iodine element, which is obviously a chemical changed The raw materials of the chlor-alkali industry and the soda ash industry have table salt.

That's right, just look at the two industries.

The answer is d.

The total reaction of chlor-alkali industry is 2NaCl+2H2O=2NaOH+Cl2 +H2 The total reaction of soda ash industry is NaCl+CO2+NH3+H2O=NaHCO3+NH4Cl, 2NaHCO3=Na2CO3+CO2+H2O

The marine element is bromine.