MAGNESIUM - Mg

Properties of Magnesium:

The silver-white, relatively soft, ductile, malleable metal. On air covered with an oxide film. Passivated in cold water, concentrated sulfuric acid and hydrofluoric acid. Does not react with alkalis. A strong reducing agent, reacts with hot water, diluted acids, nonmetals. Transferred to solution by ammonium salts.


Molar mass g/mol 24.305
Density g/cm3 1.737
Melting point °C 648
Boiling point °C 1095

Methods for preparation of Magnesium:

MgO + C(coke) = Mg + CO (over 2000°C).

MgO + Ca = CaO + Mg (1300°C).

Mg3N2 = 3Mg + N2 ( 700-1500°C).

MgCl2(melt) → Electrolysis → Mg(cathode) + Cl2↑(anode).


Сhemical reactions with Magnesium:

Mg + 2H2O(hot) = Mg(OH)2↓ + H2↑.

Mg + 2HCl(diluted) = MgCl2 + H2↑.

4Mg + 10HNO3(diluted) = 4Mg(NO3)2 + 2N2O↑ + 5H2O.

Mg + 2NH4Cl(conc., hot) = MgCl2 + 2NH3↑ + H2↑.

Mg + H2 = MgH2 (175°C, pressure, catalyst MgI2).

2Mg + O2 = 2MgO (600-650°C, combustion on air),

3Mg + N2 = Mg3N2 (780-800°C, combustion on air).

Mg + Cl2(moist) = MgCl2 (normal temp.).

Mg + H2S = MgS + H2 (500°C).

3Mg + 2NH3 = Mg3N2 + 3H2 (600-850°C).

Mg + 2N2O4 = Mg(NO3)2↓ + 2NO (150°C, vaccum, in ethyl acetate).

4Mg + SiO2 = Mg2Si + MgO (below 800°C, in the atmosphere of H2),

2Mg + SiO2 = Si + 2MgO (1000°C).
 

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The double-helix structure of DNA was discovered in 1953 by James Watson and Francis Crick. The length of a single human DNA molecule, when extended, is 1.7 metres (5 ft 5 in).