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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 .
The structure of MgO 2 has been calculated as a triangular shape with the O 2 molecule binding side-on to the magnesium. This arrangement is a result of the Mg + donating charge to the oxygen and creating a Mg 2+ O 2 2−. The bond between to O 2 and the magnesium atom has an approximate dissociation energy of 90 kJ mol −1. [1]
Magnesium hydride was first prepared in 1951 by the reaction between hydrogen and magnesium under high temperature, pressure and magnesium iodide as a catalyst. [1] It reacts with water to release hydrogen gas; it decomposes at 287 °C, 1 bar: [2] MgH 2 → Mg + H 2. Magnesium can form compounds with the chemical formula MgX 2 (X=F
Although solid magnesium reacts slowly with oxygen at STP, it is capable of burning in air, generating very high temperatures, and its metal powder may form explosive mixtures with air. Oxygen is present as compounds in the atmosphere in trace quantities in the form of carbon dioxide (CO 2) and oxides of nitrogen (NO x).
There is some ambiguity at the borderlines between the groups. Magnesium , aluminium and zinc can react with water, but the reaction is usually very slow unless the metal samples are specially prepared to remove the surface passivation layer of oxide which protects the rest of the metal.
Direct reaction of magnesium with air or oxygen at ambient pressure forms only the "normal" oxide MgO. However, this oxide may be combined with hydrogen peroxide to form magnesium peroxide, MgO 2, and at low temperature the peroxide may be further reacted with ozone to form magnesium superoxide Mg(O 2) 2. [21]
Magnesium nitride reacts with water to produce magnesium hydroxide and ammonia gas, as do many metal nitrides.. Mg 3 N 2 (s) + 6 H 2 O(l) → 3 Mg(OH) 2 (aq) + 2 NH 3 (g). In fact, when magnesium is burned in air, some magnesium nitride is formed in addition to the principal product, magnesium oxide.
Reactions are usually written as forward reactions in the direction in which they are spontaneous. Examples: Reaction of hydrogen and oxygen to form water. 2H 2 + O 2 ⇌ 2H 2 O. Dissociation of acetic acid in water into acetate ions and hydronium ions. CH 3 COOH + H 2 O ⇌ CH 3 COO − + H 3 O +