Pure sulfuric acid is a colorless and tasteless liquid oil. Commonly used in H2SO4 concentrated sulphuric acid content of 98.3 percent, its density of 1.84 g cm-3, of its  The amount of concentration to 18.4 mol L-1. Sulphuric acid is a highly difficult to boiling point volatile acid, soluble in water, can be arbitrary and water than the immiscibility. Concentrated sulphuric acid solution  When the release of a lot of heat, so should be concentrated sulphuric acid diluted "acid into the water, along the wall, slowly down, constantly stirred." If the concentrated sulphuric acid in the Access to  SO3, will lead to "smoke" phenomenon, that more than 98.3 percent of the sulfuric acid known as the "smoke sulfate"  Absorbent  A bottle of concentrated sulphuric acid placed in the air, their quality will increase, the density will decrease, reducing the concentration, size larger, it is because concentrated sulphuric acid with water absorption.  ⑴ on sulfuric acid, water absorption is the nature of concentrated sulphuric acid, rather than dilute sulfuric acid in nature.  ⑵ the suction of concentrated sulphuric acid, which is concentrated sulphuric acid molecule with a strong combination of water molecules, generating a series of the hydrate stability, and emit a lot of heat: H2SO4 + nH2O == H2SO4 nH2O, the water is concentrated sulphuric acid is a chemical process Changes in the process of water absorption is the chemical nature of concentrated sulphuric acid.  ⑶ concentrated sulphuric acid can not only absorb the general state of free water (such as in the air and water), but also absorb certain crystalline hydrates (such as CuSO4 5H2O, Na2CO3 10H2O) of water.