1. The physical and chemical constant
EINECS no. : 231-231-5 dangerous gauge number: 81007 character: colourless clear thick oily liquid. Components/composition: 98.0% sulfuric acid (thick) 70% (also belong to the sulfuric acid density: 98% of sulfuric acid is 1.84 g/mL molecular weight: 98 g/mol, amount of substance concentration: 98% of sulfuric acid mol/L relative density 18.4:1.84. Boiling point: 338 ℃ solubility: miscibility with water and ethanol freezing point: anhydrous acid in 10 ℃, 98% sulfuric acid coagulation in 3 ℃. Central atom hybridization method: sp3 [2]
2. Dissolve exothermic
Release a large amount of heat when sulfuric acid to dissolve, so dilute sulfuric acid should be "acid into the water, along the wall, slowly pour, stirring constantly." If the water in concentrated sulfuric acid, the temperature will reach 173 ℃, lead to acid splash, cause potential safety hazard. Sulfuric acid is a colorless viscous, oily liquid, is a kind of high boiling point volatile acid, soluble in water, can be in any ratio and water miscibility. [2]
3. The azeotrope
(melting point, 10 ℃) boiling point: 290 ℃ acid (100%), the boiling point: 338 ℃ acid (98.3%), but 98.3% of sulfuric acid is not the most stable, boils it down as a part of the 98.3% of sulfuric acid, become 338 ℃ (sulfuric acid aqueous solution) azeotrope. Heating the concentration of concentrated sulfuric acid is only up to 98.3%. [2]
4. Water imbibition
It is a good desiccant. To dry acidic and neutral gas, such as CO ₂, H ₂, N ₂, NO ₂, HCl, SO ₂, etc., cannot be alkaline dry gas, such as NH3, and with a reducing gas under normal temperature, such as H2S. Sulfuric acid water absorption is a physical process Water and the water is very different: sulfuric acid absorption is free of water molecules, water molecules can be bound. Taught in schools are involved in, have the following description: "the water because of sulfuric acid and water combination can generate different composition of natural gas hydrates, at the same time gives off heat. Sulfate hydrate - H2SO4 · H2O, - H2SO4 · 2 H2O, - H2SO4 · 4 H2O, etc., when reduce the temperature of sulfuric acid solution, the hydrate precipitation in the form of crystal." High school stage of sulfuric acid dissolution is a physical process is wrong! Place a bottle of sulfuric acid exposure in air, its quality will increase, the density is reduced, reduced concentration, volume change, solute quality mark will be smaller. This is because the concentrated sulfuric acid with water
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