Chemistry Problems Master Advance, Chemistry Problems I m online, etc., please say the details of th

1.Organic chemistry has two major effects: the electron effect.

Spatial effects. Electron effects are divided into: induction effects.

Conjugation effect. Electron-withdrawing base.

The set of repulsions (electron donors) is in terms of the electron effect.

As a rule. When attached to a saturated atom of a group, the main consideration is the induction effect.

At a deep level, the induction effect is mainly based on the electron shift of the bond formed externally due to the electronegativity of the electron, or the ability of the central atom to bind the electrons outside the nucleus.

So the induction effect.

The electronegativity (more negative than the central atom) is the electron-withdrawing group.

The small one is the electron-donor base.

For the same atom, judging by the amount of S content contained in it, the more S components, the stronger the binding on electrons outside the nucleus, resulting in the enhancement of the ability of the nucleus to pull electrons and the electron aspiration.

Methyl sp3 hybrids component is the least. So. Alkyne.

Both alkenes are electron-withdrawing for saturated carbon.

In the same way, benzene is also electron withdrawing (only the induction effect).

Generally speaking. The induced effect is transmitted only along the decreasing bonds, and is negligible after 3 carbons.

When the central atom is not saturated, the conjugation effect should be considered, and generally when the atom is connected to the unsaturated atom, the atom is easy to be conjugated with the p orbital to form a delocalized bond, if the orbit is relatively close.

The outermost electrons of the atom under discussion are relatively surplus and tend to give electron conjugation outward, and the positive charge is generally electron-withdrawing conjugation.

The characteristics are: positive and negative alternately, and the intensity does not decrease with length.

If the group under discussion is an unsaturated group, the electronegativity is judged to be positive and negative, and then the electrons are deflected according to the alternation of positive and negative.

General conclusions. The inducing effect is denoted by i, given as +, suction as -, and the conjugation effect is denoted by c, given as +, and suction as -on

ICC is predominant (electron-giving when connected to an unsaturated system) CLBR

ici is the main (in the case of conjugation, the orbit does not match).

The hydrocarbon group is the electron-donor group.

The more substituents, the more electrons are doned.

Unsaturated electron-withdrawing base.

Alkenyl. Alkyne.

Benzene. Nitro.

N+ (quaternary ammonium salt) carbonyl.

Carboxyl. 2.Acidity can be determined by ionization H+ difficulty, at a deep level, the atom attached to H binds the ability of H, that is, how many electrons he has, the more H, the more difficult it is to lose, and the less it is to lose.

Hydroxyl groups are used as the research object (only the influence of the outside world on the hydroxyl group is considered).

The alcohol hydroxyl group is attached to the saturated carbon, and the hydroxyl oxygen is donated, so that the electron density increases, the binding to H is enhanced, and H is difficult to ionize.

The phenolic hydroxyl group is connected to the aromatic ring, and the aromatic ring absorbs electrons (-c, +i), which reduces the electron density, weakens the binding to H, and makes H easy to ionize.

The carboxyl hydroxyl group is attached to the carbonyl group, and the carbonyl group withdraws electrons (-c), which reduces the electron density, weakens the binding to H, and makes H easily ionized (the carbonyl group withdraws electrons more than the benzene ring).

The benzene ring is oxygenated by the atom +c

The i carbonyl group is +c by the oxygen atom because there is also an oxygen, but it is not easy to absorb electrons, so that the oxygen atom has less electron density.

4.Phenol can be oxidized (phenolic hydroxyl) to quinone.

Carboxylic acids cannot, and already in the final state carboxylated carbon can no longer be oxidized.

Formic acid can be (aldehyde group).

1 About electron-withdrawing groups and repulsion groups:

Both are induced reactions by organic chemistry. Induction effect refers to the phenomenon that after an atom or group is introduced into an organic molecule, the density distribution of bonding electrons in the molecule changes, so that the chemical bond is polarized, which is called inductive

effects）。The induction effect is characterized by the shift of the electron cloud along the bond and weakens or disappears as the carbon chain grows.

An atom or cluster of atoms that has a stronger ability to attract electrons (more electronegative) than hydrogen atoms.

Such as—x, —oh, —no2, —cn, etc.).

Electron aspiration. Group; Meaning the electron cloud of the entire molecule is biased towards the substituent.

An atom or cluster of atoms that has a weaker ability to attract electrons than hydrogen atoms.

such as alkyl group) has.

Give electrons. The group, which represents the electron cloud that deviates from the substituents throughout the molecule.

The difference between phenyl and alkyl is that the phenyl group is a cyclic conjugated bond; Alkanes, on the other hand, are sp3 hybridized linear bonds; The two behave differently when the induced response occurs.

2r-oh，ar-oh，ch3-cho—oh；The difference is in the group linked to the hydroxyl group; Alkyl, aromatic hydrocarbon, and carbonyl group, respectively; Alkanes belong to electron-donor groups; The latter two belong to electron-withdrawing groups; The electron-repelling property of alkanes makes the electrons tend to the hydroxyl group, and the hydroxyl hydrogen is naturally not easy to ionize; In the carboxylic acid molecule, the carbonyl group is conjugated with the hydroxyl hydrogen, and the electrons are uniformly distributed across the carbonyl group. The electron cloud is far away from carboxyl hydrogen; So carboxyl hydrogen is the easiest to ionize; So finally sort r-oh<

The reaction of ar-oh3 with sodium should be pure phenol, because the water in the solution also reacts with sodium; And it reacts faster than phenol.

Phenol has strong reducing properties and can be oxidized to quinone, because OH- has an effect on the phenyl group and affects the stability of the large bond; to manifest its inherent instability; The carbonyl group and the hydroxyl group in the carboxylic acid form a conjugated system. And it is already highly oxidized, so it cannot be oxidized.

The problem with catalysts, because catalysts change the course of a reaction, simply means that a very high-energy process that needs to be crossed becomes n small high-energy processes, and the activation energy can be reduced

The second question is answered very completely, and I'm going to talk about error generation, which is divided into systematic error and random error

Systematic error, also known as measurable error, is the main error of quantitative analysis, which has a great impact on the accuracy of the measurement results. It is caused by certain and regular factors in the analysis process, and the influence on the analysis results is relatively fixed.

1) Method error.

This error is due to the analytical method itself. For example, in gravimetric analysis, the dissolution loss of precipitation or the error caused by the adsorption of certain impurities; In titration analysis, the reaction is not carried out completely, the influence of interfering ions, the non-conformity of the titration endpoint and the equivalence point, and the occurrence of other side reactions, etc.

Yes. systematically influence the assay results.

2) Instrument error.

This is mainly caused by the instrument itself being inaccurate or not calibrated. For example, the balance, the scale of the gauge and the measuring instrument are not accurate enough, etc., and the measurement results will be incorrect in the process of use.

3) Reagent error.

Caused by impurity of reagents or trace impurities in distilled water.

The cause of random error is different from systematic error, it is caused by some accidental factors (such as small fluctuations in temperature, humidity and barometric pressure of the environment at the time of measurement, small changes in instrument performance, etc.).

1.In junior high school it is like this, two elements when reading. But not absolutely, there are other substances in high school that may also be read.

2.Whether or not to read the number of atoms has nothing to do with valency, it is a convention such as Fe2O3, which can be read as iron oxide or ferric oxide. When there are multiple valencies of the same element, the number of atoms that make up it can generally be read.

1: Well, it is only needed when the chemical valence of the element is large (CO2, SO2).

2: One is enough, such as potassium permanganate.

In fact, this student doesn't have to be so serious, he won't take these exams in the exam.

1 No, for example, dodecahydrate and potassium aluminum sulfate, dodecahydrate is 12 water molecules.

2 I don't know about that, probably, but there are exceptions, and hydrogen peroxide doesn't seem to be.

Well, it can help a lot.

This relates to the name of the substance in chemistry, in general, we usually say its common name, but sometimes we have to say the number of atoms. In fact, whether it is a common name or a reading atom, it is just a title, and in the end it is necessary to remember the chemical formula, I suggest that you say more about the number of atoms, and the common name should also be remembered.

3. 1. The molar mass is numerically the same as the relative molecular mass.

2. The molar mass unit is g mol

The soda ash and hydrochloric acid reaction is step-by-step:

I Na2CO3 HCl NAHC3 NACLII NAHCO3 HCl NaCl H2O CO2 1l1mol l Soda ash solution - N(Na2CO3) 1mol; 200 ml of 6mol L of hydrochloric acid - N(HCl).

When the two react, the first reaction occurs, 1molNa2CO3 and 1molHCl react to form 1molNaHCO3, and due to the excess HCl, there is still left, so it will react with the reaction to form again.

Under v(CO2).

The weak acid corresponding to carbonate is bicarbonate, so when hydrochloric acid is insufficient, bicarbonate will be generated first, because the ability of carbonate to bind protons is stronger than bicarbonate, that is, alkaline is stronger than bicarbonate, on the contrary, if soda ash is dropped into hydrochloric acid, the final generation is CO2, because bicarbonate can not stably exist in a strong acidic environment, so carbonate directly reacts with hydrochloric acid to form CO2, this concept is very important, we must remember ......

It can be calculated that HCl with 1mol of Na2CO3 is co-generated as NaHCO3 (carbonate is more basic than bicarbonate) because hydrochloric acid is added to soda ash dropwise.

1molnahco3

When you continue to add it, CO2 will start to be generated.

That is, the remaining HCl is reflected with 1mol of NaHCO3, so the co-generated CO2 is under the standard condition.

The soda ash and hydrochloric acid reaction is step-by-step:

1. Na2CO3 HCl NaHCO3 NACL2, NaHCO3 HCl NaCl H2O CO2 1l1mol l soda ash solution - N(Na2CO3) 1mol;

200ml of 6mol L of hydrochloric acid - N(HCl) When the two react, the first reaction occurs, 1molNa2CO3 and 1molHCl react to form 1molNaHCO3, but due to the excess HCl, there is still left, so it will be reformed with the reaction in the standard condition. Bottom, v(CO2).