Specific surface area

The internal surface area of ​​porous or granular solids encompasses all surfaces contained therein, including those that are located between grains and within pores. The actual measured size of the inner surface is the specific surface area.

In contrast, it is at the outer surface around the outside of directly visible surface, ie those that would be obtained in the packaging of the material system.

Basics

All porous ( sponge-like or foam-like ) materials as well as bulk material ( as powder and bulk materials ) are traversed by numerous cavities. Since all chemical reactions much depend on how big is the attack surface compared to the volume, the inner surface is of great importance. For example, fine metal shavings are highly flammable, while this to larger pieces of metal is not the case (although with larger pieces of metal, the better heat dissipation is relevant, as a result of this heat dissipation the ignition temperature is reached more slowly than with fine chips ). And the weathering stability of a rock is essentially determined by its size and the number of cracks. Similar effects also exist in numerous purely physical phenomena, such as capillary action and moisture storage, thermal insulation, light reflection and others.

Specific surface area

The specific surface area (of English. Surface) is determined with a surface measurement.

By mass

The mass-based specific surface

Specifies the size (sqm ) kg of a material has (unit).

By volume

The volume- based specific surface

Indicates which surface A (sqm) one cubic meter of material has (unit).

The smallest specific surface area ( at a given volume) of the ball has: