(1) concentrated H2SO4: used to dry H2, O2, N2, CO, CO2, SO2, HCl and other gases, but it can't dry water-soluble alkaline gases, such as NH3.

(2)NaOH solid: It is used to dry H2, O2, N2, CO, NH3 and other gases, but it cannot dry gases that are acidic when dissolved in water, such as CO2, SO2, HCl and other gases.

(3) Anhydrous CuSO4: It has strong water absorption, turns blue after water absorption, and generates CuSO45H2O. Usually, anhydrous CuSO4 is used to check whether some substances contain water.

(4) Quicklime (CaO): It easily reacts with water to generate hydrated lime Ca(OH)2, which is often used as a desiccant in food bags.

(5) Alkaline lime: a mixture of CaO and NaOH, which is used as NaOH solid.

(6)MgCl2 and CaCl2: They also have strong water absorption, and are often used to absorb the water vapor generated after the reaction in some experiments.

What are the common desiccants in junior high school chemistry?

Classification of gases

1, according to the acidity and alkalinity,

Acid gases: CO2, SO2, NO2, HCl, Cl2, H2S, HBr, HI, etc.

Alkaline gas: only NH3

Neutral gases: H2, O2, CH4, CO, CH2=CH2, C2H2, N2, etc.

2. accord to that redox strength at room temperature,

Strongly reducing gases: H2S, HBr, HI, SO2, etc.

General gases: H2, O2, CH4, etc.

Types and selection of gas desiccant

1, commonly used gas desiccant according to the acidity and alkalinity can be divided into three categories:

① Acidic desiccant, such as concentrated sulfuric acid, phosphorus pentoxide and silica gel. Acidic desiccant can dry acidic or neutral gases, such as CO2, SO2, NO2, HCl, H2, Cl2, O2 and CH4.

② Alkaline desiccants, such as quicklime, alkali lime and solid NaOH. Alkaline desiccants can be used to dry alkaline or neutral gases, such as NH3, H2, O2 and CH4.

③ Neutral desiccant, such as anhydrous calcium chloride and anhydrous copper sulfate, can dry neutral, acidic and alkaline gases, such as O2, H2 and CH4.

According to the oxidizability of desiccant, it can be divided into two categories.

① Strong oxidizing desiccant: concentrated sulfuric acid

② General desiccants: phosphorus pentoxide, silica gel, quicklime, alkali lime, solid NaOH, CaCl2, CuSO4, etc.

1. concentrated sulfuric acid. It is water-absorbent. Can't dry ammonia, etc. 2. Alkaline lime (a mixture of sodium hydroxide and calcium oxide) cannot dry carbon dioxide and sulfur dioxide. 3. Sodium hydroxide. Water absorption. 4. calcium oxide. Can react with water. 5. Calcium chloride. It becomes crystalline hydrate after absorbing water. Can dry all gases in junior high school.

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What are the desiccants in junior middle school chemistry?

Solids include alkali lime, dry water, acid gas removal, anhydrous calcium chloride, water removal, quicklime, and water removal, and calcium hydroxide can also absorb alkaline gas. Liquid with concentrated sulfuric acid can't dry alkaline gas.

What are the common food desiccants in junior high school?

There is a quicklime desiccant, and its component is calcium oxide, which is irreversible. There is a silica gel desiccant. Silica gel is generally used in laboratories, but rarely used in food. It is reversible. You can use it again as long as you take it to the oven for high temperature heating. There is calcium chloride desiccant, which becomes calcium chloride. There is also a montmorillonite desiccant, which is a natural component, non-toxic and harmless. Has no harm to human body, and has good adsorption capacity.

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What can be used as desiccant in junior high school chemistry?

1. concentrated sulfuric acid. It is water-absorbent. Can't dry ammonia, etc.

2. Alkaline lime (a mixture of sodium hydroxide and calcium oxide) cannot dry carbon dioxide and sulfur dioxide.

3. Sodium hydroxide. Water absorption.

4. calcium oxide. Can react with water.

5. Calcium chloride. It becomes crystalline hydrate after absorbing water. Can dry all gases in junior high school.