Either gives you a chemical formula, how can you tell if it s acidic or basic? 40

By composition: contains H (hydrogen ions) are acidic,,, contains OH- (hydroxide) is alkaline,,, soluble salts contain anions that can be combined with H+ to be weakly acidic Alkaline ,,, contain cations that can be combined with OH- to form a precipitate (but not precipitate, because there is too little OH- in the water) or weak alkali Acidic.

Judging by the definition.

Acids are compounds that are separated in solution and are all H+ cations. For example, H2SO4.

A base is a compound in which the anions separated in solution are all oh-. For example, NAOH.

If it is an acid with hydrogen ions, or a base with hydroxide, some hydroxides appear in the form of hydration, which is also alkaline but not alkaline.

Weak alkali salt: Because the weak alkali ion combines with the hydroxide ion ion of the water ionization, the ionization balance of the water is broken, and the water is continuously ionized, which increases the concentration of hydrogen ions in the solution, which is acidic, and the weak acid salt is the opposite.

In the chemical formula, who is strong is the other, the anion is strong and the cation is strong and the cation is alkaline, which is determined by the hydrolysis of the salt!

Compounds that produce all anions are oh ions are called bases, compounds that produce cations that are metal cations or ammonium ions and acid anions are called salts, and compounds that produce cations that are all hydrogen ions are called acids.

To put it simply: strong acids and weak alkali salts are acidic; Strong alkali and weak salts are alkaline. (Whoever is strong becomes whom).

1. Judge the strength of acidity

1) The most advanced oxygen-containing acids of different elements, the stronger the non-metallic nature of acid-forming elements, the stronger the acidity;

2) Oxygen-containing acids of different valences of the same element, the higher the valency of the element, the stronger the acidity;

3) For the same main group element, the more the number of nuclear charges, the larger the atomic radius, and the stronger the acidity of hydride;

2. Judge the alkalinity: the stronger the metallicity of the element, the stronger the alkalinity of the hydrate of the most advanced oxide.

First of all, you have to determine whether the substance is an electrolyte or not, and it makes sense to analyze electrolytes.

1. Acid or alkali.

In inorganic chemistry, compound solutions that generally only use hydrogen ions as cations are acidic; A solution of a compound with only hydroxide as an anion is alkaline.

2. Salt. Look at whether the salt solution is acidic or alkaline, as long as you understand the composition of that salt. Inorganic salts are generally divided into strong acids and strong alkali salts (salts formed by strong acids and strong bases), strong acids and weak alkali salts (salts formed by strong acids and weak bases), weak acids and strong alkali salts (salts formed by weak acids and weak bases), and weak acids and weak alkali salts (salts formed by weak acids and weak bases).

Strong acids and alkaline salts.

Generally, strong acids and strong alkali salts are neutral. Because strong acids and strong bases can be completely ionized in water, they will not cause the equilibrium change of hydrogen ions and hydroxide ions in water, that is, they will not be hydrolyzed, so the solution is neutral.

Strong acid and weak alkali salt.

Generally, strong acids and weak alkaline salts are acidic. Because the anions of strong acids are completely ionized and do not hydrolyze; The cation of the weak base will be hydrolyzed in the water, which will combine the hydroxide ions, so that the concentration of hydrogen ions will rise, so the solution is acidic.

Weak acids and strong alkaline salts.

Generally, weak acids and strong alkaline salts are alkaline. Because the cation of the strong base is completely ionized and will not be hydrolyzed; The anions of weak acids will be hydrolyzed in water, combining hydrogen ions, making the concentration of hydroxide ions rise, so the solution is alkaline.

Weak acid and weak alkali salt.

The acidity and alkalinity of the weak acid and weak alkali salt solution depends on which acid or base is stronger, and the general solution will show the nature of the stronger side.

Summary: In fact, the acidity and alkalinity of the salt solution are relatively easy to distinguish. That is, the acid and base that make up this salt, whoever has the stronger solution will show whose nature.

Purely acidic: look at the oxidation of his non-metal, the stronger the oxidation, the stronger the acidity of the hydrate corresponding to it. The oxidation increases along the cycle and decreases according to the main group.

Purely alkaline: look at the reducibility of his metal, the stronger the reducibility, the stronger the alkalinity of the hydrate corresponding to it. The reducibility decreases along the period and increases according to the main family.

Salts: Judged to be the same strength of the acid-base composition of salts (neutral).Strong acid, weak alkali salt (acidic) or strong alkali weak salt (alkaline).

The acidity can be judged by comparing the stability of the negative ions, and the alkalinity can be judged by analyzing the electron cloud density and spatial effect of the central atom.

The acidity and alkalinity of organic compounds can be used to separate compounds in organic chemical migration, and the differences in the activity of substances in the reaction field can be compared.

The answer is supplemented. 1. Acidity and alkalinity can be determined by analyzing electronic effects (induction effect, conjugation effect).

The induction effect glorifies the acidity and alkalinity of a substance: the greater the ability of a substance to give protons, the more acidic it is. And the ability to give protons depends largely on the ability of the substituents around the molecule to lose protons to form negative ions to disperse the charge.

The more dispersed the charge of the formed carboxanion is, the stronger and more stable the ability to donate protons. Therefore, any structural factor that disperses the charge can increase the stability of the carboanion and decrease the stability of the negative ion. In general, electron-withdrawing substituents increase the acidity of organic matter, while electron-donating substituents reduce their acidity.

The conjugation effect also affects acidity and alkalinity. In a conjugated system, electron delocalization expands the range of electron motion and makes the system stable. The carbonyl group in a carbonyl compound is a polar double bond, which makes its -hydrogen somewhat acidic due to the induction effect and the conjugation effect.

However, the acidity of hydrogen varies depending on the chemical environment.

2. For organic compounds with different structures, the acidity and alkalinity of the chemical compounds can be compared through some reactions.

Some chemical substances have large differences in their structure, and it is difficult to determine the relationship between their acidity and alkalinity through the spatial effect of electronic effects, such as: sodium acetylene, sodium amino, sodium hydroxide, these three compounds are all alkalis, and the order of their alkalinity is not known at a glance, but it can be compared by the relevant reactions existing in the literature, and the acidity and alkalinity of organic Taiwan substances can be seen at a glance

hc=chnanh2-onehc=cnah3

hc==cnaho

1 HC==CH

Naoh It is not difficult to see from the above that according to the rule of weak acid and weak alkali reaction of strong alkali and weak acid, the alkalinity of sodium aminogen is stronger than that of sodium acetylene, and the alkalinity of sodium acetylene is stronger than that of sodium hydroxide, on the other hand, it also shows that acetylene is more acidic than ammonia, and acetylene is weaker than water After knowing this, it is not difficult for us to understand that the reaction involving sodium acetylene and some other carboanion ions often must be carried out under anhydrous conditions It is also an effective means to determine the acid-alkaline relationship between chemical substances through some reactions

In short, to judge the acidity and alkalinity of organic compounds, we can consider the following aspects: for organic compounds with similar structures, their acidity and alkalinity can be compared by electronic effects (including induction effect and conjugation effect); For organic compounds with different structures, their acidity and alkalinity should be judged according to the relevant reactions in the literature.

Hello! In inorganic chemistry:

Non-metallic oxides are acidic oxides.

Most metal oxides are basic oxides.

The hydrate corresponding to the acidic oxide is an acid.

The hydrate corresponding to the basic oxide is the base.

Strong acid and weak alkali salt, its aqueous solution is acidic.

The aqueous solution of strong alkali and weak acid is alkaline.

Salts that can ionize metal ions and hydrogen ions are called acid salts.

Such as sodium bicarbonate. (However, its aqueous solution is alkaline).

Salts that can ionize acid ions and hydroxide ions are called basic salts.

Such as: basic copper carbonate.

In organic chemistry: (relatively).

Compounds containing carboxyl groups are more acidic.

Compounds containing amine groups are mostly alkaline.

Please correct the inappropriateness! Best wishes!

The salts of the strong acid and alkaline type are neutral, and the case is NaCl Kno3

Weakly acidic and strong-alkaline salts are alkaline Na2CO3 NaHCO3 CH3COONA

The salts of the strongly acidic and weakly basic form are acidic NH4NO3 (NH4)2SO4