32. ALUMINIUM AND III-A ELEMENTS OF GROUP.

STAY IN THE NATURE

Contains in crust boron - 0,0016%, aluminum - 7,57%, gallium - 0,0014%, indium - 0,00001%, thallium - 0,00003%. Aluminosilicates (Al, O, Si, alkali and alkaline earth metals) - clays-Al2O3 · nSiO3 · mH2O, bauxites - Al2O3 · nH2O, nephelines - KNa3[AlSiO4]4 meet in the nature only in the form of connections, most often

Physical properties of metals and boron.

Element	Boron B	Aluminum Al	Gallium Ga	Indium In	Thallium Tl
Property
Order number of element	5	13	31	49	81
Relative atomic mass	10,811	26,982	69,723	114,82	204,383
Temperature of melting, C0	2400	660	29,8	156	305
G/cm3 density	1,86	1,75	1,55	2,64	3,61
Oxidation levels	+3	+3	+1,+3	+1, +3	+1, +3
Primeneiye of metals	spetsialyny alloys, borating of surfaces	constructional material, aluminothermy, the conductor in electrical equipment, etc.	alloying of semiconductors	alloying and receiving semiconductors

RECEIVING

Electrolysis of Al2O3 at 950 0C in fusion of Na3 cryolite [AlF6] on the cathode: Al3 ++ 3e=Al0 on the coal anode (it is spent in electrolysis process): O2-2e=O0 C+O=CO; 2CO+O2=2CO2

 

CHEMICAL PROPERTIES OF ALUMINIUM
1. With oxygen	4Al+3O2=2Al2O3
2. With halogens	2Al+3Cl2=2AlCl3
3. With sulfur when heating	2Al+3S=Al2S3
4. With carbon	4Al+3C=Al4C3
5. Aluminothermy	8Al+3Fe3O4=4Al2O3+9Fe
6. With water (after destruction of oxide film)	2Al+6H2O=2Al (OH)3+3H2
7. It is dissolved in alkalis	2Al+2NaOH+6H2O=2Na [Al(OH)4] + 3H2
8. Reacts with acids	2Al+6HCl=2AlCl3+3H2
9. With the nitric and concentrated chamois acids in the cold do not react. When heating:	Al+6H2SO4 (конц.) =Al2(SO4) 3+3SO2+6H2O Al+6HNO3=Al(NO3)3+3NO2+3H2O

 

COMPOUNDS OF ALUMINIUM
Al2O3 aluminum oxide - very firm (corundum, ruby), refractory - 2050 0C. It is not dissolved in water.	Al (OH) 3 hydroxide
Polucheniye:2al (OH)3=Al2O3+3H2O Properties: amphoteric oxide Al2O3+6HCl=2AlCl3+3H2O Al2O3+2NaOH+3H2O=2Na [Al(OH)4] For transfer in soluble state use alloyage: Al2O3+2NaOH=2NaAlO2 (metaaluminate)	Polucheniye:alcl3+3 (NH3·H2O) of =Al (OH) 3 +NH4Cl Svoystva:amfoterny basis Al(OH)3+HCl=AlCl3+3H2O Al(OH)3+NaOH=Na [Al(OH)4]

Many salts well of rastvorima in water, they are hydrolyzed (acid reaction): Al3 ++ H2OAl(OH)2 ++ H +

Other elements: boron,gallium,indium, thallium.

   

 

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