Comparing the acidity of several chemicals, the most acidic of the compounds is

The general formula of oxygenated acid can be written r-o-h like this, the easier it is to lose h, the more acidic it is. It depends on the force of the r-o side on h. The above three acids are the substitution of acetic acid in the two positions, only F, Cl and H are not the same, F and Cl have a certain electron withdrawing effect, but the F radius is smaller than Cl, and the electron withdrawing effect is larger than Cl, so the electrons are biased towards the R group, which reduces the electron cloud density on O, so that H is easier to remove, so the acid replaced by F is more acidic.

For the last acid, H does not have an electron-withdrawing effect, and even has an electron-donating effect, so its effect is exactly the opposite of F and Cl, so it is the weakest acidity.

After the hydrogen atoms on the saturated monocarboxylic acid hydrocarbon group are replaced by halogen, hydroxyl group, nitro group and other electronegative groups, because these groups have the effect of attracting electrons, the carboxyl group has an absorbent induction effect, which reduces the electron cloud density on the carboxyl carbon atom, the negative charge is more stable, the polarity is enhanced, and the hydrogen is easily ionized, so the acidity is enhanced. Fluorine is more non-metallic than chlorine, and you know.

The acidity of acetic acid derivatives mainly depends on the stability of CoO-, and the molecular polarization of FCH2CoOH after dissociation due to the induction effect, which leads to the above results.

The most acidic compound is carbonic acid.

Carbonic acid is a dibasic weak acid with the chemical formula H2CO3 and a very small ionization constant. At room temperature and pressure, the concentration of carbon dioxide saturated solution is about , pH is, pka1=, pka2=.

Sometimes, carbonic acid can also cause problems in our daily lives. Carbon dioxide gas on the ground dissolves in water to form carbonic acid. When surface water seeps into the ground, carbonic acid is also carried to the ground, and chemically reacts with calcium carbonate, which is insoluble in water, in underground limestone to form calcium bicarbonate that is soluble in water.

Water containing calcium in bicarbonate is called "hard water", so underground water is considered "hard water". The water in the rivers does not contain calcium bicarbonate and is not "hard water".

In some places, tap water is used as groundwater, and when the water is boiled, the calcium bicarbonate in the water is heated and decomposed into calcium carbonate, carbon dioxide and water. Calcium carbonate is a sediment that is insoluble in water, it is deposited on the walls of kettles and boilers, and over time it becomes a layer of white and very hard substance, called pot scale (commonly known as water alkali).

This layer of calcium carbonate has poor thermal conductivity, so fuel is wasted when boiling water. If the scale in the boiler and pipes is too thick, there is also a danger of **. Therefore, in industrial production, the "hard water" is always chemically removed or reduced to soften the calcium carbonate before use.

Why acids have similar chemical properties

Different acid solutions contain the same hydrogen ions, so acids have similar chemical properties.

The definition of acid is that the cations ionized are all hydrogen ions in order to be called acids, and since they are all hydrogen ions, there is a certain similarity in properties.

Because the essence here is hydrogen ions, of course, the presence of other anions will affect the chemical properties of the acid, for example, hydrochloric acid has the reducing property because of chloride ions, nitric acid has strong oxidation because of nitrate, concentrated sulfuric acid has strong oxidation because of the concentration relationship, to see clearly the factors that determine the chemical properties.

For example, hydrochloric acid contains hydrogen ions and chloride ions, and sulfuric acid solutions contain hydrogen ions and sulfate ions, and their solutions all contain the same hydrogen ions, so they can all react with acid-base indicators, active metals, basic oxides, bases and salts, and have similar chemical properties.

According to the degree of ionization of acid in aqueous solution, there are strong acids and weak acids, and it is generally believed that strong acids are completely ionized in aqueous solutions, such as hydrochloric acid and nitric acid; Weak acids are partially ionized in aqueous solutions, such as acetic acid, carbonic acid.

The ionization equilibrium of weak acids present in aqueous solution is as follows

Ha] [H+] A-] is the amount concentration of the substance of Ha H+ A-, respectively, which is the ionization equilibrium constant of the weak acid Ha. For example, at 298K, the ionization constant of acetic acid is hydrofluoric acid. The ionization equilibrium constant varies slightly with the concentration and temperature of the weak electrolyte.

At a certain temperature, the ionization degree of weak acid increases due to the thinning of the solution, such as the ionization degree of acetic acid, which is completely ionized when diluted indefinitely.

The chemical properties of acids are:

1. The acid solution can react with the acid-base indicator. The purple litmus test solution turns red when it meets acid, and the colorless phenolphthalein test solution does not change color when it meets acid. Note that the chromogenic substance is an indicator.

2. Acids can react with a variety of active metals, usually to produce salts and hydrogen. Only metals that precede hydrogen in the order table of metal activity can react with dilute acids (HCl, Hso) to produce hydrogen. Metals located after hydrogen cannot react with dilute acids (HCl, Hso), but can react with concentrated sulfuric acid and concentrated nitric acid.

3. Acid can react with alkaline oxides to form salt and water: H so +Cao == Caso +H O

4. Acid can react with certain salts to form new acids and new salts: H so + BACL === Baso + 2HCl

5. Acid and alkali neutralization reaction to generate salt and water: H so Ba(OH) === Baso (white precipitate) 2HO

Acid: Chemically refers to a compound that is completely hydrogen when ionized in solution and can turn purple litmus solution red. In a narrow sense, it can also be divided into inorganic acids and organic acids. The acid-base proton theory holds that acid is a substance that can release protons, which is collectively called acid.

1) Elemental metal + acid - salt + hydrogen (displacement reaction).

Zinc and dilute sulfuric acid Zn + H2SO4 = ZnSO4 + H2 Phenomenon: There is a combustible gas generated.

Iron and dilute sulfuric acid Fe + H2SO4 = FeSO4 + H2 Phenomenon: Turns into a light green solution and at the same time releases gas + Hg

2) Basic oxide + acid --salt + water.

Iron oxide and dilute hydrochloric acid reaction: Fe2O3 + 6HCl === 2FeCl3 + 3H2O Phenomenon: red solid dissolves to form yellow solution Iron oxide and nitric acid reaction Fe2O3 + 6Hno3 ==2Fe(NO3)3+3H2O Phenomenon:

The red solid dissolves, forming a yellow solution.

3) Acidic oxide + alkali - salt + water.

Caustic soda deteriorates when exposed to air: 2NaOH + CO2 ==== Na2CO3 + H2O

Caustic soda absorbs sulfur dioxide gas: 2NaOH + SO2 ==== Na2SO3 + H2O

H2O(4) acid + base – salt + water.

Hydrochloric acid and caustic soda react: HCl + NaOH ==== NaCl + H2O phenomenon: not obvious.

Hydrochloric acid and potassium hydroxide reaction: HCl + KOH ==== KCl + H2O

5) Acid + Salt – Another acid + another salt.

Marble reacts with dilute hydrochloric acid: CaCO3 + 2HCl === CaCl2 + H2O + CO2 Phenomenon: Bose solids dissolve to produce a gas that can make pure lime water turbid.

Sodium carbonate reacts with dilute hydrochloric acid: Na2CO3 + 2HCl === 2NaCl + H2O + CO2 Phenomenon: Generate a gas that can make pure lime water turbid.

Indicator: litmus solution.

Indicator: The acid can make the purple litmus solution turn red, and it will not change color when encountering phenolphthalein.

Reactive metals: Acids react with reactive metals to produce hydrogen and salts. For example, Fe + H2SO4 = FeSo4 + H2

Alkali: Acids react with alkalis to give salt and water. For example, NaOH + HCl = NACl + H2O

Salt: Acid reacts with salt to obtain new acid and new salt. For example, CaCO3 + 2 HCl = CaCl2 + CO2 + H2O

Metal oxides: Acids react with metal oxides to give salt and water. For example, cuo + h2so4 = h2o + cuso4

Junior Chemistry Experiment - Chemical Properties of Acids.

Indicator: Reactive Metal:

Alkali: Salt: Metal Oxide:

nm gadfly 24

The chemical properties of acids of concern are:

1. The acid solution can react with the acid-base indicator. The purple litmus test solution turns red when it meets acid, and the colorless phenolphthalein test solution does not change color when it meets acid. Note that the chromogenic substance is an indicator.

2. Acids can react with a variety of active metals, usually to produce salts and hydrogen. Only metals that precede hydrogen in the order table of metal activity can react with dilute acids (HCl, Hso) to produce hydrogen. Metals located after hydrogen cannot react with dilute acids (HCl, Hso), but can react with concentrated sulfuric acid and concentrated nitric acid.

3. Acid can react with alkaline oxides to form salt and water: H so +Cao == Caso +H O

4. Acid can react with certain salts to form new acids and new salts: H so + BACL === Baso + 2HCl

5. Acid and alkali neutralization reaction to generate salt and water: H so Ba(OH) === Baso (white precipitate) 2HO

1. The acid solution can react with the acid-base indicator. The purple litmus test solution turns red when it meets acid, and the colorless phenolphthalein test solution does not change color when it meets acid. Note that the chromogenic substance is an indicator.

2. Acids can react with a variety of active metals, usually to produce salts and hydrogen. Only metals that precede hydrogen in the order table of metal activity can react with dilute acids (HCl, H2SO4) to produce hydrogen. Metals located after hydrogen cannot react with dilute acids (HCl, H2SO4), but can react with concentrated sulfuric acid and concentrated nitric acid.

For example: Cu 2H2SO4 (concentrated) CuSO4 SO2 2H2O

3Cu 8Hno3 (dilute) 3Cu (NO3)2 2No 4H2O

It can be seen that no hydrogen is produced in the reaction of metals with concentrated sulfuric acid and nitric acid, which is why the laboratory cannot use concentrated sulfuric acid and nitric acid to react with zinc to produce hydrogen.

3) Acids can react with basic oxides to form salts and water: H2SO4 + CA == CaSO4 + H2O

4) Acids can react with certain salts to form new acids and salts: H2SO4 + BACL2 === BASO4 + 2HCl

5) Acid and alkali neutralization reaction to produce salt and water: H2SO4 BA(OH)2 === BASO4 (white precipitate) 2H2O

Reacts with indicators, all metals except gold, non-coexisting ionic salts (including weak acids and strong alkali salts), bases, other acids (such as HCl and HNO3, concentrated H2SO4 and most non-metallic hydrides), amphoteric hydroxides, some non-metallic elements (e.g., S, C), all metal oxides (i.e., basic oxides), and other ions (e.g., AlO2-).

It reacts with salt to form a new acid new salt H2SO4+2NaCl=Na2SO4+2HCl

React with alkali to form salt and water HCl+NaOH=NaCl+H2O, react with active metal, release H2 2mg+2HCl=2mgCl+H2, make purple litmus solution red, and there is no equation.

1、b＞c＞a＞d

First of all, the general principle is that the electron-withdrawing group on the benzene ring increases the acidity, and the electron-donating group weakens the acidity, so BC a d.

Then compare b and c.

The main difference between metalocation and paraposition is the conjugation effect.

The electron cloud density of meta-carbon atoms is higher, the attraction of electrons on the carboxyl group is less, and the dissociation of carboxylic acids is weaker. So meta-acidity is the weakest.

2、a＞c＞b＞e＞d

First of all, it needs to be noted that potassium hydrogen terephthalate is actually PK2 compared to terephthalic acid.

So divided into 2 groups: ABC DE.

Of the three substances of ABC, -COOH is an electron-withdrawing group, which is similar to the role of -NO2 in the previous question. So ac b.

Comparing A and C, the -1 valence acid group of phthalic acid can form intramolecular hydrogen bonds, which is particularly stable.

So a carboxyl group on h ionization becomes easy, so a c.

Comparing d and e, d is actually the structural formula in the figure above.

Since H is confined to the hydrogen bond, ionization is difficult. Hence e d.

3. The alkalinity of amines is related to solvents. It's hard to say.

Organic Chemistry in College??

The more electron withdrawing groups, the stronger the ability, the stronger the acidity, because it is easier to ionize hydrogen ions, in addition, the analysis of proximity is more complicated, generally to consider the electron withdrawing induction benefit, but also to consider the steric hindrance and other comprehensive factors, so whether it is to judge alkaline, or acidic, the group has the greatest impact on him. The parasite has a certain electron-donor conjugation effect, so it should be c>b>a>d (methyl electron-donor group, nitro-electron-withdrawing group).

2. Classification does, the acidity of de ac b salt is not as strong as acid, so de is at the end, d>e, dibasic acid is stronger than monobasic acid, so there are a>c>b>d>e

3, EHB ACD FG First of all, FG should be the largest, with two electron-withdrawing groups, F>G, followed by BEH, H>E>B, then A>C>D, so F>G>H>E>B>A>C>D