What is the chemical nature of alkali and what are the properties of alkali?

There are 4 chemical properties of alkalis, also known as the general properties of alkalis. It is important to note that some properties are only applicable to soluble bases.

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

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

2. Alkali can react with acid to form salt and water (this kind of reaction is usually called neutralization reaction).

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

ca(oh)2+h2so4=caso4+2h20

3. The alkali solution can react with non-metallic 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

4. The alkali solution can react with the salt to generate new 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

That is, alkali substances can react with which substances, such as reacting with acid to form salt and water, alkali solution can make phenolphthalein test solution red, alkali solution reacts with carbon dioxide, etc

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

The 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.

Solubility decreases with increasing temperature. Marble contains a small amount of calcium hydroxide, which is used in laboratories.

and hydrochloric acid reaction to produce carbon dioxide.

Chemical properties of alkalis in junior high school chemistry.

Properties of bases:1. Alkali solution can be combined with acid-base indicator.

Function. 2. Alkali can react with non-metallic elements.

3. Alkali can react with acid to form salt and water.

4. Alkaline solution can be combined with acidic oxides.

reaction, salt and water are generated.

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

6. Alkali reacts with organic matter to hydrolyze it (the property of some alkalis).

Precautions for using "alkali":1. Do not soak the food in the lye solution to avoid the rotting of the raw materials, as long as the appropriate concentration of alkaline water is used.

Rinse the ingredients several times.

2. Alkali. It is an inorganic substance.

It has no nutrients in itself, but its role in food cooking cannot be underestimated, and the aqueous solution of alkali is an electrolyte.

It can enhance the water absorption ability of protein molecules in food raw materials (such as squid) and speed up the growth rate of raw materials, but it is necessary to pay attention to the quantity, method and time of alkali used to prevent food raw materials from being too thorough, too rotten or even deteriorated.

The above content reference: Encyclopedia-alkali.

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.

reaction, salt and water are generated.

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.

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 both sexes.