Superficial destruction of a surface by friction, pressure, ulceration, or trauma. The wearing away of a tooth by chemical or abrasive action. Also called odontolysis. erosion. The gradual wearing away of land surface materials, especially rocks, sediments, and soils, by the action of water, wind, or a glacier.
In chemistry, the molar mass M is a physical property defined as the mass of a given substance (chemical element or chemical compound) divided by its amount of substance. The base SI unit for molar mass is kg / mol.
The molar mass of a substance is its relative formula mass in grams. The unit for molar mass is g/mol. For example: the M r of water is 18, so its molar mass is 18 g/mol.the M r of calcium hydroxide is 74, so its molar mass is 74 g/mol.he molar mass is the relative formula mass of a substance in grams (measured in g/mol). Mass is conserved in chemical reactions, allowing the mass of a reactant or product to be calculated if the masses of the other substances in the reaction are known.