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Magnesium oxide (Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg 2+ ions and O 2− ions held together by ionic bonding .
Crystalline magnesium oxide, or periclase, has a calculated lattice energy of 3795 kJ mol-1 which must be overcome for it to go into solution or for reaction to occur. Reactive magnesia is essentially amorphous magnesia with low lattice energy and is made at low temperatures and finely ground. CCM is manufactured worldwide.
Electrolysis of the resulting molten magnesium chloride is conducted at 700 °C (1,292 °F): [6] MgCl 2 → Mg + Cl 2. Aluminium metal is produced from aluminium oxides by electrolysis of a molten mixture of sodium hexafluoroaluminate and alumina at 950 °C (1,740 °F). This conversion is called the Hall-Haroult process. [7]
Enthalpies of melting and boiling for pure elements versus temperatures of transition, demonstrating Trouton's rule. In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure.
The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition.
In both, magnesium oxide is the precursor to magnesium metal. The magnesium oxide is produced as a solid solution with calcium oxide by calcining the mineral dolomite, which is a solid solution of calcium and magnesium carbonates: CaCO 3 ·MgCO 3 → MgO·CaO + 2 CO 2. Reduction occurs at high temperatures with silicon.
The manufacturing process for soda–lime glass consists in melting the raw materials, which are the silica, soda (Na 2 O), hydrated lime (Ca(OH) 2), dolomite (CaMg(CO 3) 2, which provides the magnesium oxide), and aluminium oxide; along with small quantities of fining agents (e.g., sodium sulfate (Na 2 SO 4), sodium chloride (NaCl), etc.) in a glass furnace at temperatures locally up to 1675 ...
The concept of lattice energy was originally applied to the formation of compounds with structures like rocksalt and sphalerite where the ions occupy high-symmetry crystal lattice sites. In the case of NaCl, lattice energy is the energy change of the reaction Na + (g) + Cl − (g) → NaCl (s) which amounts to −786 kJ/mol. [2]