What are the general properties of alkali and alkali, and what are the general properties of alkali

In the same way as acids, we can define a base as: the anions formed when ionized are all oh ions. Here we should also pay special attention to the keywords "anion", "all", and "oh".

Let's take the common sodium hydroxide and calcium hydroxide as examples to illustrate the general properties of alkalis.

Common bases and the general properties of bases.

The general properties of the base are sodium hydroxide calcium hydroxide.

The alkali turns the purple litmus solution blue and the colorless phenolphthalein solution red. Sodium hydroxide turns the purple litmus solution blue, and the colorless phenolphthalein solution turns red. Calcium hydroxide turns purple litmus solution blue, and colorless phenolphthalein solution turns red.

Acidic oxide + alkali salt + water 2NaOH + CO2 = Na2CO3 + H2O Ca(OH)2 + CO2 = CaCO3 + H2O

Acid + Base Salt + Water NaOH + HCl = NaCl + H2O Ca(OH)2 + H2SO4 = CaSO4 + 2H2O

Salt + alkali Another salt + another alkali 2NaOH+CuSO4=Na2SO4+Cu(OH)2 Ca(OH)2+Na2CO3=CaCO3 +2NaOH

Note: 1) Only soluble bases can react with some non-metallic oxides, which are acidic oxides. Most acidic oxides are soluble in water and combine with water to form acids.

2) When salt and alkali react, both must be soluble, and one of the products is a precipitate, for the reaction to proceed.

3) Write the chemical equation for the reaction of alkali with certain metal oxides.

Some people find it difficult to write chemical equations for such reactions, so you can first write a chemical equation for the reaction of non-metallic oxides with water to form oxygenated acids, and then write the products in terms of the exchange of components between oxygenated acids and bases. The two equations are combined into a single chemical equation. For example, sulfur trioxide reacts with sodium hydroxide

The inductive method interprets the general properties of bases.

There are five common properties of alkalis, which are:1. The alkali solution can react with the salt to generate neoalkali (relatively weak alkali) and new salt.

2. Alkali can react with non-metallic elements. For example, the disproportionation reaction of sulfur and alkali.

3. The alkali solution can interact with the acid-base indicator, and the purple litmus test solution turns blue (the phenomenon is not obvious, but there is a change), and the colorless phenolphthalein test solution turns red (the phenomenon is obvious).

4. Alkali can react with acid to form salt and water. This type of reaction emits a lot of heat and is known as a neutralization reaction.

5. The alkali solution can react with acidic oxides to form salts and water.

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.

General properties of bases:

1. The alkali solution can react with the acid-base indicator, the purple litmus test solution turns blue when it encounters alkali, and the colorless phenolphthalein test solution turns red when it encounters alkali. Insoluble alkali that cannot discolor acid-base indicators.

2. Alkali can react with acidic oxides to form salt and water.

3. Alkali can neutralize and react with acid to produce salt and water.

4. Alkali can react with certain salts to form new alkali and new salts.

Extended Information: Reaction: Can react with acids.

For example: (1) Cu(OH)2+2HCI=CuCl2+2H2O

2)mg(oh)2+2hci=mgci2+2h2o

Chemical properties: 1. The alkaline solution is alkaline pH>7, (aqueous solution, 25 degrees Celsius).

2. Alkali can make the purple litmus solution turn blue.

3. Alkali can make the colorless phenolphthalein reagent red.

4. The reaction between alkali and acid-base indicator is a chemical reaction. Grip and tie sale.

Acidic oxides: oxides that react with bases to form salts and water (usually without involving a change in valency). Such as CO2, SO2, SIO2, SO3, MN2O7, etc.

Note: Acid oxides include most non-metal oxides and a few metal oxides (e.g., Mn2O7), but a few non-metal oxides are not acid oxides, such as neutral oxides such as CO, H2O, etc.

Acidic oxides can mostly be dissolved in water under normal conditions, and combine with water to form acid, but this is not the inevitable general property of acidic oxides, such as SiO2 can not react with water under ordinary conditions.

What are the general properties of alkalis are as follows:

1. It can neutralize with acid to generate salt and water.

2. It can make the acidic indicator become alkaline, such as phenolphthalein indicator, which is dark red in alkaline solution.

3. It can react with certain metal ions to form salts, such as sodium hydroxide and silver chloride to form silver hydroxide.

4. It has good solubility in water and can form alkaline aqueous solution, such as sodium hydroxide.

5. The ionization energy of the base is small, and it is easy to lose one or more electrons to form cations, such as sodium hydroxide (NaOH) ionized into Na+ and OH- ions in water.

6. In the reaction with acid to form salt and water, the heat of hydrolysis of alkali is larger, so it is necessary to pay attention to safety during the reaction.

The chemical base is the anions produced during ionization, all of which are compounds of hydroxide ions. There are two types of bases: soluble and insoluble. The bases studied in general chemistry are soluble bases. Soluble bases have five general properties, and insoluble bases have one general properties.

A common chemical equation for the reaction with a crack base.

1. Reaction of alkali and acid: alkali + acid salt + water; For example: sodium hydroxide + hydrochloric acid sodium chloride + water; naoh + hcl → nacl + h2o

2. Reaction of alkali and metal: alkali + metal salt + hydrogen; For example: sodium hydroxide + aluminum, aluminium chloride + hydrogen; 2naoh + 2al → 2naalo2 + h2

3. Reaction of alkali and acidic oxide: alkali + acidic oxide salt + water; For example: sodium hydroxide + sulfuric acid sodium sulfate + water; 2naoh + h2so4 → na2so4 + 2h2o

4. Reaction of alkali and salt: alkali + salt salt + alkali; For example: sodium hydroxide + calcium carbonate calcium chloride + water + carbon dioxide; 2naoh + caco3 → cacl2 + h2o + co2

5. Reaction of alkali and carboxylic acid: alkali + carboxylic acid salt + water; For example: sodium hydroxide + acetic acid sodium acetate + water; naoh + ch3cooh → ch3coona + h2o

A base is a compound in which all the anions ionized in an aqueous solution are OH-. There are five points in the general properties of alkalis:

1. The reaction between the alkali solution and the acid-base indicator: make the purple litmus test solution turn blue, and make the colorless phenolphthalein test solution red.

2. The alkali solution can react with acidic oxides to generate salt and water. (e.g. CO2 + Ca(OH)2==CaCO3 +H2O).

3. The alkali solution can react with non-metallic oxides to generate salts and water. (e.g. H2CO3+Ca(OH)2==CaCO3 +2H2O).

4. The alkali solution can react with salt to generate new alkali and new salt. (e.g. Ca(OH)2+Na2CO3=CaCO3 +2NaOH).

5. The alkali solution can react with acid to form salt and water. (e.g. HCl+Naoh=NaCl+H2O).

According to the solubility of alkali in water, it can be divided into soluble alkali Huaiyu and insoluble alkali. Among the common bases, sodium hydroxide, potassium hydroxide, barium hydroxide, etc. are soluble bases; Nickel hydroxide and calcium hydroxide belong to microlead-nano-soluble bases; Others belong to insoluble bases, such as magnesium hydroxide, copper hydroxide, iron hydroxide, etc.