A, the classification of common desiccant

Desiccants in middle school can be divided into three types according to their acidity and alkalinity:

1. Acid desiccant: concentrated sulfuric acid, phosphorus pentoxide and silica gel.

① concentrated sulfuric acid (strong oxidizing acid)

② Phosphorus pentoxide (acidic white powder)

(3) Silica gel (it is a translucent porous solid with large internal surface area, which has good adsorption and strong adsorption on water. Silica gel containing cobalt salt is called chromotropic silica gel, which is blue when it does not absorb water and pink when it is saturated with water. )

2. Alkaline desiccant: alkali lime, Ca0

(1) alkali lime (it is a white solid, mainly composed of CaO and NaOH)

(2) ②Ca0 (it is a white solid, alkaline oxide),

3. Neutral desiccant: anhydrous calcium chloride

Second, the classification of common gases

Common gases in middle school can be roughly divided into three types according to their acidity and alkalinity:

1. Acid gases: carbon dioxide, sulfur dioxide, nitrogen dioxide, chlorine, hydrogen sulfide, hydrogen chloride, hydrogen bromide, hydrogen iodide, etc.