High School Chemistry Questions What s wrong with me doing this? ）

Why do you need to subtract 5 from 50?

The total HCL used is 50ml, and it is completely reflected.

You can think of it this way, the amount of NaCl, Na+ and Cl- substances in the final solution is equal, so the amount of HCl used is equal to the amount of Na ion substances 1:1, so the HCl used in the initial reaction should also be added, not subtracted.

And that hydrochloric acid is, you wrote it.

First, the mistake is to substitute the concentration of HCl for the wrong one, which should be, no, resulting in an extra 0 after the decimal point of the result.

Second: the change is in two stages:

Remaining Na2CO3: Na2CO3 + HCl = NaCl + NaHCO3, consume 5 ml of hydrochloric acid.

All NaHCO3 (including NA2CO3 generated): NAHCO3 + HCl = NACl + CO2 + H2O, consume 50-5 = 45 ml.

Your calculations based on the conservation of Na+ ions are very good, which means that you can think big about the problem. But you ignore the CL- that goes into the solution, so it leads to an error in the result.

Correct solution: add hydrochloric acid to co-contain HCl:, according to the conservation of Na+, know that NaHCO3 and Na2CO3 co-contain Na+:, and you can also know that NaHCO3 is before deterioration, and the mass is.

4 iron sulfide is calculated according to 480, why is 8 sulfur dioxide not counted as 512? There is actually a problem with the proportional relationship, since the iron sulfide has been calculated according to 480, there is no need to consider the relationship between 4 moles and 8 moles.

To sum up, there are two problems:

1 Forget to include the relative molecular mass of sulfur dioxide.

2 The ratio was double-counted (the relative molecular mass is 480, which takes into account the ratio, and 4 moles and 8 moles are again a recalculation. But this ratio is enough to consider once).

What's more, the conservation of sulfur can be used to calculate the results directly, and to put it bluntly, the mass of sulfur in the original iron sulfide and the sulfur in the final 98% concentrated early branch bend sulfuric acid should be the same.

1: The molecular formula of glucose is C6H12O6, which can only be said that a glucose molecule contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.

2: Glucose and sucrose are not isomers, but they are not homologues either. (The former is a monosaccharide and the latter is a polysaccharide).

The first sentence is wrong on the molecule; There are no water molecules in the glucose molecule.

The second sentence is wrong with the congeners. See the definition of homologues for details.

1.Glucose is a molecule that contains three elements and is made up of these three elements, and there is no water molecule in it.

2.Isomers are those with the same molecular formula but different structures. The molecules of glucose and sucrose are not the same.

Glucose should be a mixture.

Glucose and sucrose are isomers.

1. The structure of the periodic table is examined.

Looking at the periodic table, one can see that between group ia and group iiia, a gradual increase in transitional elements is obtained.

If it's the first cycle, it's A+2

If it's the first cycle, it's A+12

If it is the first cycle, can you see that there are also lanthanide and actinide elements, which are A+26

2. Tested 18 particles of the electronic system.

10 electronic system is necessary to know, there is.

Atom --- ne

Molecules--- CH4, NH3, H2O, HF

Ions--- O2-, F-, Na+, Mg2+, Al3+, NH4+, Oh-, H3O+, NH2-

18 electronic systems are derived on this basis, there are:

Atom --- ar

Molecules--- SIH4, PH3, H2S, HCl, F2, H2O2, N2H4, C2H6, CH3F, CH3OH, CH3NH2, HONH2, etc.

Ions--- S2-, Cl-, Hs-, K+, Ca2+, etc.

The four substances of A, B, C, and D contain 2 or 3 elements respectively, and their molecules each contain 18 electrons--- which are found in the molecules.

A is a gaseous hydride that ionizes two anions in water step by step. --A is H2S

B has the same molar mass as oxygen,-- B is 32, then B is CH3OH methanol, which must contain polar bonds, but no non-polar bonds.

The mass ratio of each element in Ding and A is the same,-- Ding is H2O2, then Ding must contain -1 valence element, which is the O element.

1 is +12 for cycles 4 or 5 because there are 10 subfamily elements in between.

2 A is H2S D is H2O2 The mass ratio of each element refers to the mass ratio of two elements in the same substance B to A False B can be CH3OH without non-polar bonds.

If you have a problem you can hi me

1 For example, the atomic number of K is 19, and the atomic number of GA is 31, a difference of 12

2 A is H2S, D is H2O2, and the mass ratio of each element is 1 to 16

You can see it by looking at the periodic table.

With the addition of the Excess Element, the difference between the first and third main families is 12.

Hard water refers to water that contains more soluble calcium and magnesium compounds. Such as some well water, spring water. However, if it contains less soluble calcium and magnesium compounds, it is not hard water.

A displacement reaction is a reaction in which one element and one compound produce another element and another compound. Whereas, ionic reactions are reactions that can be ionized in water. In junior high school, we learned that hydrogen reduces copper oxide H2+CuO=δ=Cu+H2O, and carbon reduces some metal oxides such as:

c+feo=δ=fe+co↑。None of these are carried out in water, but they are all displacement reactions.

1.If 1 ton of water contains only one calcium ion, magnesium ion, can it be called hard water?

2.It is true that the displacement reaction that occurs in the solution is a particle reaction, but the displacement reaction also has a dry displacement reaction in which the solid and the solid or the solid and the gas occur under the condition of heating or high temperature, which is not a particle reaction.

(1) Look at the definition of hard water, you will know that the hardness of water (also called salinity) refers to the amount of calcium salt and magnesium salt dissolved in water. The hardness of the content is large, and the hardness is small. 1 liter of water containing 10 mmGCAO (or equivalent to 10 mmGCAO) is called 1 degree.

Soft water is water with a hardness of less than 8, such as rain, snow, purified water, etc.; Water with a hardness greater than 8 is hard water, such as mineral water, tap water, and surface water and groundwater in nature.

2) The displacement reaction does not necessarily involve ions.

Displacement reaction is a chemical reaction in which an element reacts with a compound to form another element and a compound, and any displacement reaction belongs to a metathesis reaction, including the reaction between metals and metal salts, and the reaction between metals and acids.

A chemical reaction with the participation of ions. The essence of an ionic reaction is a change in the concentration of certain ions. Common ionic reactions are mostly carried out in aqueous solutions.

According to the reaction principle, ionic reaction can be divided into four types: metathesis, salt hydrolysis, redox and complexation. It can also be divided into interion, ion-molecule, ion-atom and atom reactions according to the particles participating in the reaction. When an extremely concentrated electrolyte reacts with a solid substance, it is necessary to determine whether it is an ionic reaction based on the nature of the reaction.

All water contains calcium and magnesium ions (except distilled water).

Displacement reactions are not all ionic reactions, take a good look at the book.

1）ch4 nh3 h20 hf （2）nh4+ na+ （3） oh- f-

This kind of problem can be inferred according to the periodic properties of the elements, taking the first question as an example, if the number of protons and electrons of the four chemical formulas is equal, the hydrides of the elements in the same period can be considered, because their proton numbers increase sequentially, as long as the number of hydrogen atoms is reduced sequentially to form hydrides of the same period, the conditions can be satisfied.

I have a review material in my space.

Redox reactions are ionic reactions organic.