BORON - B
Properties of Boron:
Nonmetal. Gray-black (crystal) or brown (amorphous). Refractory, very hard, brittle. Chemically passive. Does not react with hydrogen, water, diluted acids, diluted alkalis into the solution. Reacts with water steam, concentrated nitric acid, halogen, nitrogen, hydrogen fluoride and hydrogen sulfide, ammonia and alkalis when heated.
Molar mass | g/mol | 10.811 |
Density | g/cm3 | 2.340 |
Melting point | °C | 2075 |
Boiling point | °C | 3700 |
Methods for the preparation of Boron:
B2H6 = 2B + 3H2 (300-500°C)
B2O3 + 2Al = Al2O3 + 2B (800-900°C)
2BCl3 + 3H2 = 2B + 6HCl (800-1200°C)
2BI3 = 2B + 3I2 (over 700°C or on light)
Сhemical reactions with Boron:
2B + 3H2O(steam) = B2O3 + 3H2 (700-800°C).
B + 3HNO3(hot, conc.) = B(OH)3↓ + 3NO2↑.
2B(amorphous) + 2NaOH(conc.) + 6H2O = 2Na[B(OH)4] + 3H2↑.
4B + 4NaOH + 3O2 = 4NaBO2 + 2H2O (350-400°C).
4B + 3O2 = 2B2O3 (700°C, burning on air).
2E + 3E2 = 2BE3 (30°C, E = F; over 400°C E = Cl, Br, I).
2B + 3S = B2S3 (over 600°C).
2B + N2 = 2BN (900-1000°C).
B + P(red) = BP (900-1200°C).
4B + C(graphite) = B4C (over 2000°C, impurity B13C2).
2B + 6HE = BE3 + 3H2 (400-500°C; E = F, Cl).
2B + H2S = B2S3 + 3H2 (800-900°C).
2B + 2NH3 = 2BN + 3H2 (1000-1200°C).
5B + 3NO = B2O3 + 3BN (800°C).
2B + 3CO = B2O3 + 3C(graphite) (1400°C).
4B + 3CS2 = 2B2S3 + 3C(graphite) (930°C).
4B + 3SiO2 = 2B2O3 + 3Si (1300-1500°C).
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