Chemical properties of alkalis, what are the chemical properties of alkalis?

1.Soluble alkalis can make the indicator appear different colors, can make the litmus solution appear blue, and can make the phenolphthalein solution appear red.

2.Soluble bases can react with non-metallic oxides to form salts and water (not neutralization reactions)3 Soluble bases can react with soluble salts to form new salts and new bases, which is a metathesis reaction.

Chemical properties common to all bases:

It reacts with acid to produce salt and water, which is a neutralization reaction.

Alkali. Non-metallic oxides.

Salt. Water. Caustic soda deteriorates when exposed to air: 2NaOHCO2

na2co3

H2O caustic soda absorbs sulfur dioxide gas: 2NaOHSO2NA2SO3

H2O slaked lime deteriorates in air: Ca(OH)2CO2CaCO3

H2O2) base.

Acids --- salts.

Water. Hydrochloric acid and caustic soda react: HCLnaoh

naclh2o

3) Alkali. Salt.

Another alkali. Another salt.

Calcium hydroxide with sodium carbonate: Ca(OH)2

na2co3

caco3↓+

2NaOH4) alkali solution can make the phenolphthalein reagent red, and make the purple litmus reagent blue.

Bases have four major chemical properties:

1.Reacts with an indicator (litmus.

Phenolphthalein. Methyl orange).

2.It reacts with acids to form salts and water.

It reacts with acidic oxides to also form salts and water.

It reacts with salts to form new salts and bases.

Special case: reaction with amphoteric substances {

alal2o3

al(oh)3

Weak acid and weak alkali salt.

amino acids, etc.

Chemical properties of alkalis in junior high school chemistry.

Chemical properties of alkalis in junior high school chemistry.

Chemical properties of bases:

1) Reaction with indicator: make the red litmus paper blue, colorless phenolphthalein.

Turns red and makes methyl orange.

Yellow in color. 2) React with acid to form salt and water.

3) with acidic oxides.

The reaction produces salt and water.

4) React with salt to form new alkali and new salt. Such as:

FeCl3+3NaOH Fe(OH)3+3NaCl5) insoluble base is easy to decompose. Such as:

cu(oh)2＝cuo+h2o

Chemical properties of alkalis in junior high school chemistry.

Chemical properties of bases:

1. Alkali + non-metallic oxide salt + water.

Example: Ca(OH)2 + CO2 ====CaCO3 + H2O2, alkali + salt neoalkali + new salt.

Example: Ca(OH)2+Na2CO3====2NaOH+CaCO3 3, alkali + acid water + salt.

For example: HCl+NaOH====NaCl+H2O4, alkali can react with acid-base indicator.

Example: Purple litmus solution turns blue when exposed to alkali.

The colorless phenolphthalein test solution turns red when exposed to alkali.

It undergoes a neutralization reaction with acids to produce salts and water.

Reacts with active metals to generate H2 and salts.

With salt, new alkali and new salt are generated.

Can be phenolphthalein solution reddening.

I develop a color on the left side of the pH trial production.

Certain metal oxides react with water to form their bases.

It can react with acids to form salts and water. It can react with acidic oxides to form salts and water4It can make purple litmus blue1 and make colorless phenolphthalein red.

2. The reaction substance H(+)OH(-)=H2O3

Reacts with non-metallic oxides, acids, litmus, phenolphthalein.

Produces insoluble hydroxide precipitates.

For example, 2NaOH + MgCl2 = Mg(OH)2 + H2O or produce gas NaHCO3 + NaOH = Na2CO3 + H2O + CO2 or a weak electrolyte (this is rare).

The conditions are the same as those for metathesis reactions.

It reacts with acids to form salts and water.

Reacts with non-metallic oxides to form salts and water.

It reacts with salts to form new salts and bases.

Make the purple stone test solution blue.

Colorless phenolphthalein turns red.

OH- ions can be ionized in water.

Definition of base: All anions ionized in water are oh- and are bases.

1.Discoloration of acid-base indicators.

2.Reacts with certain salts.

3.Reacts with certain metal oxides.

4.Reacts with acids.

In the theory of acid-base ionization, alkali refers to the compound that ionizes anions in aqueous solution, all of which are OH-; In acid-base proton theory, a base refers to a compound that can accept protons; In acid-base electron theory, a base refers to an electron donor.

1. The alkali solution can interact with the acid-base indicator.

The alkali solution turns blue when it encounters purple litmus solution (the phenomenon is not obvious, but there is a change), and it turns red when it encounters a colorless phenolphthalein solution (the phenomenon is obvious).

2. Alkali energy reacts with non-metallic elements

The disproportionation reaction of chlorine gas with alkali, such as:

Cl2+2NaOH = NaCl+NaCl+H2O (Br2, I2 are similar).

The disproportionation reaction of sulfur with alkalis, such as:

3s+6naoh=na2so3+2na2s+3h2o

Reaction of silicon with bases, such as:

si+2naoh+h2o=na2sio3+2h2↑

3. Alkali can react with acid to produce salt and water (this kind of reaction is usually called neutralization reaction, and this kind of reaction releases a lot of heat h=

For example, hydrated lime (calcium hydroxide) is commonly used in industry to neutralize wastewater containing excessive sulfuric acid.

ca(oh)2+h2so4=caso4+2h2o

4. The alkali solution can react with acidic oxides to generate salt and water.

For example, the most common reaction of this type is the reaction of carbon dioxide in the laboratory to test with clarified lime water, but this type of reaction is not a metathesis reaction.

co2+ca(oh)2==caco3↓+h2o

In addition, there are: 2naoh+so2==na2so3+h2o

This reaction does not conform to the exchange of components between two ionic compounds, so it is not a metathesis reaction.

5. The alkali solution (relatively strong alkali) can react with salt to generate neoalkali (relatively weak alkali) and new salt.

For example, this kind of reaction is common in the preparation of sodium hydroxide in the laboratory, and the reaction between alkali and salt has two requirements, one requires that the alkali and salt involved in the reaction be soluble in water, and the other requires that there is precipitation, gas or water in the product.

ca(oh)2+na2co3=caco3↓+2naoh

Bases have four major chemical properties:

1.Reacts with indicators (litmus, phenolphthalein, methyl orange).

2.It reacts with acids to form salts and water.

3.It reacts with acidic oxides to also form salts and water.

4.It reacts with salts to form new salts and bases.

Special case: reaction with amphoteric substances {

Alkali can react chemically with acid, the general formula is salt + water, for example, hydrochloric acid reacts with caustic soda: HCl + NaOH ==NaCl + H2O

It can react with acidic oxides, and the general formula is salt + water liquid dust, for example, caustic soda deteriorates when exposed to air: 2NaOH + CO2 ==Na2CO3 + H2O

It can be used in some salt reactions, and the general formula is another base + another salt, for example, calcium hydroxide and sodium carbonate: Ca(OH)2 + Na2CO3 ==CaCO3 + 2NaOH

Chemical properties of bases:1. Alkali energy reacts with the indicator: the purple litmus solution turns blue, and the colorless phenolphthalein solution turns red.

2. Alkali energy reacts with acidic oxides.

3. The ionized anions in the alkali are all OH ions.

4. Alkali can react with acid (acid-base neutralization reaction).

Common basesCalcium hydroxide Ca(OH)2, commonly known as clarified lime water and slaked lime, can be prepared by the reaction of quicklime (i.e., calcium oxide) with water, and a large amount of heat will be released during the reaction. Calcium hydroxide is commonly used in agriculture to neutralize acidic soils, and it is also used to prepare the pesticide Bordeaux liquid. The main ingredient of triad soil and lime slurry in daily life is hydrated lime.

In addition, a clear aqueous solution of calcium hydroxide is often used in laboratory tests for carbon dioxide. With the increase of temperature, the solubility decreases. Marble contains a small amount of calcium hydroxide, which is reacted with calcium carbonate and hydrochloric acid to produce carbon dioxide in the laboratory.