资源简介

(共41张PPT)
Group V A or 15
nitrogen, phosphorus, arsenic, antimony and bismuth
Dinitrogen
N/N is chemically very unreactive, mp –210 oC, bp –195.8 oC its great bond strength, Hdiss = 945.41 kJ/mol, dN-N = 109.76 pm, and great thermodynamic stability causes many nitrogen compounds to be endothermic.
The N2 lone pairs are very low in energy and are much less available for donation than the isoelectronic CO.
The * molecular orbitals are very high in energy ( bonds are very strong) and -backbonding is less favored.
A large HOMO-LUMO energy gap makes it hard to promote electrons or reduce dinitrogen.
Dinitrogen is a non-polar molecule. isoelectronic with: CO, NO+, CN-, C22-, and similar to HC2-, H2C2.
Hydride: Ammonia
Oxides
Compounds of As, Sb and Bi
mp. bp. low high
AsH3 SbH3 BiH3
basicity high low
spontaneous ignition：
stability high low
月
月
胂 弟 必
pyrolysis：
Hydrides:
Identification of As：
Marsh test ：
Mix sample, Zn and dilute HCl or H2SO4，produced gas passes through hot glass tube。
Arsenic Mirror
Gutzeit's test ：
microscale
Oxides and Hydroxides of M(III)
Oxides and Their Hydrates
Amphotericity：
Oxides and Hydroxides of M(V)
hydrates
unstable
medium weak
M(III) as Reductants (Decrease from As to Bi)
Cl2 can be substituted by H2O2
Redox Properties
M(V) as oxidants (increase from As to Bi)
(identification for Mn2+)
H3AsO4 can oxidize I2 only at acidic condition。
=0.5748V
I2+2e- 2I-
=0.5345V
Summary：
As(Ⅲ) Sb(Ⅲ) Bi(Ⅲ)
As(Ⅴ) Sb(Ⅴ) Bi(Ⅴ)
basicity
reducing power
acidity
oxidizing power
basicity
acidity
Salts
Hydrolysis
Oxidants (weak)
(identify Sb3+)
(identify Bi3+)
Sulfides
Insoluble in H2O and dilute acids
As2S3、As2S5 insoluble
properties：
Dissolve in oxidative acids (HNO3)
Dissolve via coordination in c-HCl
NaOH
(M=As，Sb)
Na2S
(M=As，Sb)
Bi2S3 insoluble
Dissolve in Base
Dissolve in oxidative base
(M=As，Sb)
2MS
3S
S
M
-
3
3
-
2
3
2
+
2MS
3S
S
M
-
3
4
-
2
5
2
+
NaBiO3+6HCl(c) == Bi3++ Cl2↑+ Na+ + 3H2O+ 4Cl－
Bi(OH)3+Cl2+3NaOH == NaBiO3↓+2NaCl+3H2O
5NaBiO3+2Mn2++14H+ == 2MnO4－ +5Bi3++7H2O +5Na+
H3SbO4+2HCl == H3SbO3+Cl2+H2O
——inert pair effect
2Sb3＋ + 3Sn == 2Sb + 3Sn2＋
2Bi3＋ +3Sn(OH)42－ + 6OH－ == 2Bi + 3Sn(OH)62－

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