How to judge the acidity of HF, HCl, HI and H2S?

The ability to absorb electrons from F to I gradually decreases, but the radius of atoms from F to I increases, so the corresponding negative ions have a weaker attraction to H+, so the protons are more likely to dissociate. That is, the more acidic it is.

HF is very acidic, and HI is the strongest acid among anaerobic acids.

1. The atomic radius of F, Cl, Br, I increases, and the length of the covalent bond with H increases, which is easy to be destroyed by water and ionized H+, and the acidity is enhanced.

2. Hydrogen bonds are easy to form between HF molecules, so that HF associations in the same concentration of solution, resulting in a decrease in effective concentration, very little ionized H+, and very weak acidity.

hf

HF HCl Unsoluble water is a molecular state, and the strength of the acid is determined according to the concentration of hydrogen ions ionized by the acid molecule dissolved in water, which should be HCl>H2S>Hi>HFBy the way, hf is a special case, hcl, hbr, hi are all strong acids, hf is a weak acid, this is the law of the periodic table: taking the elements in the third row as the standard, the elements below the three rows are similar in nature to the elements in the third row, and the elements in the second row are special cases, cl is in the third row, br, i are four or five lines, so br, i and cl are similar in nature, so hbr, hi, hcl are strong acids, and f is in the second row, so hf is a special case, so hf is a weak acid

Look at his oxidation.

The more oxidizing it is, the less acidic it is.

Back, common strong acid HCI HBR Hi H2SO4 HNO3

HF is a weak acid is a special case, and H2S is a common weak acid.

Fluoroaluminum, bromide, iodine, and sulfur are ranked by the relative activity of the intensity.

Here all the acidity of -h depends on the electron-withdrawing strength of the adjacent carbonyl group, and the electron-withdrawing strength of the carbonyl group can be judged by the effect of the fragment on the other side of the carbonyl group.

From A to F, the fragments on the other side of the carbonyl group are H, methyl group (if you understand it as ethyl, it is all alkyl), chlorine, acetoxy, methoxy (if you understand it as ethoxy, it is also alkoxy), and hydroxyl group.

h is generally used as a zero standard, that is, it does not have electron absorption or self-confidence in giving points, so we regard a as the zero point of measurement.

The groups that have an electron-donor effect on the carbonyl group, that is, increase the electron cloud density of the carbonyl group, weaken its electron-absorbing property, and reduce the acidity of -H are:

Alkyl, alkoxy, hydroxyl.

Among them, the electron donor of the alkoxy group is stronger than the hydroxyl group, and the hydroxyl group is stronger than the alkyl group, so it is acidic a>b>f>e

ps: f This substance is placed here, extremely brainless, because there is a carboxyl group, the acidity of -h is almost negligible, and no one will use carboxylic acid to do a condensation reaction similar to hydrocarbonic acid.

It has an electron-withdrawing effect on the carbonyl group, that is, it reduces the electron cloud density of the carbonyl group and increases its electron-withdrawing properties

Chlorine, acetoxy.

Among them, the former has stronger electron withdrawing than the latter. So acidic c>d>a

Therefore, the conclusion is c>d>a>b>f>e

Acidity from strong to weak: Hi>HBR>HCl>HF, where HF is a weak acid and the rest are strong acids.

The acidity of the aqueous solution of gaseous hydride mainly depends on the degree of ionization of the gaseous hydride in the aqueous solution, and the degree of ionization is related to the polarity of the bond and the polarity of the molecule, and the enhancement of the two polarities can increase the degree of ionization.

For hydrides, increased electronegativity enhances the polarity of the bond, and an increase in the atomic radius enhances the polarity of the molecule. The electronegativity of fluorine, chlorine, bromine and iodine decreases sequentially, the polarity of the bond decreases, and the degree of ionization decreases, which is a secondary contradiction. However, the atomic radius increases significantly, the molecular polarity increases, and the degree of ionization increases, which is the main contradiction. Therefore, the aqueous solution of halogen gaseous hydride becomes more acidic with the increase of atomic number, but the difference is not very large.

Hf is a weak acid because it also has hydrogen bonds between its molecules, which weakens the ionization of Hf.

In the periodic table, the weaker the non-metallic nature of the non-hydrogen element, the stronger the acidity of the anaerobic acid. Since i, br, ci and f are in the same family, the order of acidity should be as follows: hi>hbr>hcl>hf.

The only criterion for judging the strength of acidity is to determine whether the hydrogen atoms in it are easily ionized into hydrogen ions in water. The more easily an acid ionizes, the more acidic it is.

Among the hydrohalic acids, hydrochloric acid (hydrochloric acid), hydrobromic acid and hydroiodic acid are all strong acids, and their acidity increases sequentially.

Hydrofluoric acid is a weak acid, but it becomes a strong acid when its concentration is greater than 5 mol l. The reason for this anomaly is that when the concentration of HF increases, associative ions are formed to further dissociate HF.

However, HF shows exceptions in many properties, due to the strong hydrogen bonds between HF molecules, so in hydrogen halide, it has the largest heat of melting, heat of vaporization and the highest boiling point, and the melting point is also greater than HCl and HBR. From the point of view of chemical properties, hydrogen halide and hydrohalic acid also show regular changes, and HF also shows some particularities.

The existence of the three substances is H-Cl bond, H-BR bond, H-I bond, acidity is the break of the covalent bond out of H+, so just judge which bond is easier to break, H-I bond is the longest bond length, the easiest to break, so the most acidic, I understand it this way.

It can be understood so simply that the higher the atomic number, the larger the number of protons, the more positive charges it carries, the stronger the attraction ability to the shared electron pairs, the more electron pairs are biased towards it, the easier it is to break under the action of water, the stronger the ability to release H ions, and the stronger the acidity.

Hence the higher the atomic number, the more acidic it is. These three acids correspond to the atomic number i br cl and thus are acidic hl hbr hcl.