Acid Properties: A sharp water or acid (in Latin acids means sour) is a chemical substance.
The characteristics of its aqueous solutions include sour taste, the ability to change the color of the blue to red,
And also the ability to react with bases and some special metals (such as calcium) and salt formation.
aqueous solutions have a pH less than 7.
The bottom pH means more acidity and a higher concentration of hydrogen ions.
Solutions or chemicals that have the same acidic properties are acidic.
Acid is said to be hydrogen-containing substances that can react with metals and produce hydrogen gas.
General Properties of Acids
- The ingredients with the sour taste.
- Their aqueous solution release proton ions.
- Paint the litmus paper red.
- Combined with some metals such as iron and zinc, and liberates hydrogen gas.
- Reacts with alkalis (alkalis) and forms salts.
- They react with calcium carbonate, for example, in the form of marble, so that they float and release carbon dioxide
Arrhenius’s theory of acids
When the chemical ionization concepts were clarified in aqueous solutions,
The concept of acid has changed considerably.
According to Arrhenius, acid is a is material that ionized in water, and it produces ion + H3O, which is sometimes shown as + H.
(HCl -> H + + Cl- (aq
Arnius also interpreted acidic power on this basis, saying that strong acid is almost completely ionized in aqueous solutions.
If the amount of acid dissolution is lower.
Notice that the Arrhenius concept is based on water ions.
By the definition of Arrhenius, the role of acid oxides can also be interpreted
Many oxides of non-metals react with water and produce acid,
As a result, these substances are called acid oxides or acidic acid.
N2O5 (s) + H2O → H + + NO3-aq
The Bronsted-Lowry acid-base theory
By definition, Bronsted – Lowry, the acid is a substance that gives a proton to alkali.
Acids may be molecules or ions.
By removing the proton, the acid is converted to the alkali (alkali acid 1), and by acquiring the proton, the initial opening, the open 2, becomes acid 2 (the conjugate acid 2).
Acid 2 + open 1 <- acid 1 + open 2
The strength of acids is based on their desire to lose or absorb proton.
The stronger the acid, the weaker the alkali conjugate it is.
In one reaction, the balance in the formation of acid is weaker. Perchloric acid, HClO4, is the strongest acid, and its alkali conjugate, ion perchlorate, -ClO4, is the weakest alkali, and H2, the weakest acid and its conjugate, ion-hydride, + H, is the strongest open.
Louis’s theory of acids
According to Louis, acid is a substance that can form a covalent bond by accepting an open electron pair.
In Louis’s theory, the concept of the electron pair and the formation of covalent bonding are emphasized.
Luis’s definition of things is much broader than what he has said. Chemical compounds that can play the role of acid Louis include:
- Molecules or atoms that have incomplete octaves.
(BH3 + F- → BH4- (aq
Many simple cations can play the role of acid Louis.
Cu + 2 + 4NH3 → Cu (NH3) 4 + 2
- Some metal atoms form acid in the formation of compounds such as carbonyls produced by the reaction of metal with carbon monoxide:
Ni + 4CO → Ni (CO) 4
- Compounds whose central atoms have a tiny expansion of their thickness,
In the reactions that this expansion extends to, they have an acid role,
For example, in the opposite reaction, the thickness of the central atom (Sn) extends from 8 to 2 electrons.
SnCl4 + 2Cl → SnCl6-2aq
Some compounds have acidic properties due to the presence of one or more double bonds in the molecule.
For example, CO2
Acidic Power and Molecular Structure
In order to investigate the relationship between molecular structure and acidity,
The acids are divided into two types:
Covalent hydrides and oxyacid.
Some hybrid covalent binary compounds (such as HCl, H2) are acidic.
Two factors affect the acidity of the hydride element:
Elemental electronegativity and elemental atomic size
. The acidity of the hydrides of the elements of a period increases from left to right, in line with the electronegativity of the elements.
An electronegative element takes up more electrons from hydrogen and accelerates its release as a proton.
The acidity of the hydrides of the elements of a group increases by increasing the size of the central atom.
In the second alternation: NH3> H2O> HF in group VI is as follows:
H2Te> H2Se> H2S> H2O
In these compounds, acidic hydrogen is attached to an O atom, and the change in the size of this atom is negligible.
Therefore, the key factor in the acidic power of these oxides is the electronegativity of the atom Z: H-O-Z.
If Z is a non-metallic atom with high electronegativity, it contributes to the reduction of the electron density around the O atom (in spite of intense oxygen electronegativity).
This phenomenon causes the oxygen atom to accelerate its separation by making the electron density of the H-O bond of the H atom, and make the composition acidic.
Hypocaloric acid, HOCl, is an acid of this type.
The greater the electronegativity of Z, the H-O bond electrons are far more atomic H, and it is easier to remove the proton: HOCl> HOBr> HOI.
In oxygen oxides where more oxygen atoms are attached to Z, acidity increases with increasing n
The most important strong acids
The molecules of these acids are completely ionized in dilute aqueous solutions.
Conventional acids are: chloride, iodide, nitric, sulfuric, per chloric acid.
The most important weak acids
Ionization of these acids is not complete in water and never reaches 100%.
The conventional examples are acetic acid, carbonic acid, fluoride acid, nitric acid and, to some extent, phosphoric acid.
Some uses of acids
One of the most powerful mineral acids with the formula H2SO4 is a light and dark oil.
An industrial utility that is used extensively in oil refining and in fertilizer, paint, pigments, dyes, and explosives.
An organic acid is a colorless liquid with the formula CH3COOH, which is also the basis for vinegar.
The major part of the world’s most acid-free, alcohol-based reaction is used to produce esters that are used as the best solvents in paint and polish.
Also, in pharmaceutical factories, the practice of natural rubber and the supply of artificial leather and as a solvent for many organic compounds of acetic acid is used.
A strong mineral acid with the formula HNO3, which is used by the user in nitrate fertilizers and ammonium phosphate fertilizers, nitro blast, plastics, dyes, and varnishes.
These acids, with the general formula HSO3R, where R can be methane or benzene, etc.,
Soluble in water, non-volatile and absorbent, and as emulsifying agents,
Lubricants and lubricants are used to prevent corrosion and rust.
One of the strongest mineral acids with the formula H Cl, which is a pale yellow or slightly yellowish, is very corrosive and non-flammable.
The acid is dissolved in water, alcohol, benzene and used in the acidification (activation) of oil wells, waste boilers sedimentation, food industry, cleaning of metals, and so on.