38. ELEMENTS OF SUBGROUP OF COPPER.

Properties of elements of subgroup of copper

Atomic number	Name	Electron configuration	ρ g/cm3	t0pl. 0C	t0kip. 0C	EO	Atomic radius, nanometer	Specific zlektro-pro-water content of m, mm2, ohms-1	Oxidation level
29	Cu copper	[Ar] 3d104s1	8,96	1083	2595	1,9	0,127	58,1	+1,+2
47	Ag silver	[Kr] 4d105s1	10,5	960	2180	1,9	0,144	61,0	+1
79	Au gold	[Xe]4f145d106s1	19,3	1064	2700	2,4	0,144	41,3	+1,+3

Physical properties.

High values of density, temperatures of melting and boiling.
High warm and conductivity.

Chemical properties.

Reactivity is small, decreases with increase in atomic number.

 

Copper and its connections.

Receiving

Igneous metallurgy:

CuO + C Cu + CO

CuO + CO Cu + _CO2

Hydrometallurgy:

CuO + _{H2SO4 CuSO4} + _H2O
CuSO4 + _{Fe FeSO4} + Cu

Electrolysis:

_2CuSO4 + _2H2O 2Cu + _O2 + _2H2SO4
                (on the cathode) (on the anode)

Chemical properties

 

Interacts with nonmetals at high temperatures:

2Cu + _{O2 2CuO}  
Cu + _{Cl2 CuCl2}  

Copper costs among tension more to the right of hydrogen therefore does not react with the diluted hydrochloric and sulfuric acids, but is dissolved in acids – oxidizers:

3Cu + _8HNO3 (разб.) _{3Cu(NO3) 2} + 2NO + _2H2O
Cu + _4HNO3 (конц.) _Cu(NO3)2 + 2NO2 + _2H2O
Cu + _2H2SO4 (конц.) _CuSO4 + _SO2+2H2O

Copper alloys with tin - bronze, with zinc - brass.

Cuprous compounds

 

Meet or in insoluble compounds (_Cu2O, _Cu2S, CuCl), or in the form of soluble complexes (coordination number of copper – 2):

CuCl + _{2NH3 [Cu(NH3)2]} of Cl

Copper oxide (I) - red color, receive recovery of compounds of copper (II), for example, glucose in alkaline condition:

_2CuSO4 + _C6H12O6 + 5NaOH _Cu2O + _2Na2SO4 + _C6H11O7Na + _3H2O

 

Cupric compounds

 

Copper oxide (II) - black color. It is recovered under the influence of strong reducers (for example, CO) to copper. Has the main character, when heating it is dissolved in acids:

CuO + _{H2SO4 CuSO4}   + _H2O
CuO + _{2HNO3  Cu(NO3)2} + _H2O

_{Cu (OH) 2 copper hydroxide (II)} - water-insoluble substance of light blue color. It is formed at effect of alkalis on salt of copper (II):

_CuSO4 + 2NaOH _Cu(OH)2 + _Na2SO4

When heating blackens, decaying to oxide:

 Cu (OH) 2 CuO + H2O

Typical basis. It is dissolved in acids.

_Cu(OH)2 + 2HCl _CuCl2 + _2H2O
Cu(OH)2 + ^{2H+ Cu2 +} + _2H2O

It is dissolved in ammonia solution with formation of complex connection (coordination number of copper – 4) cornflower-blue color (Schweizer's reagent, dissolves cellulose):

_Cu(OH)2 + _4NH3 [_{Cu(NH3)4](OH)2}

_{Cu2 (OH) 2CO3 malachite}. It is artificially possible to receive on reaction:

_2CuSO4 + _2Na2CO3 + _{H2O Cu2 (OH) 2CO3} + _2Na2SO4 + _CO2

Malachite decomposition:
_{Cu2 (OH) 2CO3 2CuO}  + _CO2 + _H2O

 

Silver and its connections

 

The noble metal steady on air. When tarnishing silver there is Gepar's reaction:

4Ag + _2H2S + _{O2 2Ag2S} + _2H2O

Among tension is more to the right of hydrogen therefore it is dissolved only in acids - oxidizers:

3Ag + _4HNO3 (разб.) _3AgNO3 + NO + _2H2O
Ag + _2HNO3 (конц.) _AgNO3 + _NO2 + _H2O
2Ag + _2H2SO4 (конц.) _Ag2SO4 + _SO2 + _2H2O

In connections silver usually shows oxidation level +1.
Soluble _{AgNO3 silver nitrate} is used as reactant for qualitative test of Cl-, Br-, I-:

Ag ⁺ + ^Cl-Agclbely
Ag ⁺ + ^Br-AgBr light yellow
Ag ⁺ + ^I-AgI dark yellow

(Ability of this rainfall to form soluble complex compounds decrease among AgCl – AgBr – AgI). On light silver halides gradually decay with desilverization.
At addition of solutions of alkalis to _{AgNO3 solution} the dark brown deposit of oxide _{of Ag2O silver} is formed:

_2AgNO3 + 2NaOH _Ag2O + _2NaNO3 + _H2O

Rainfall of AgCl and _Ag2O are dissolved in ammonia solutions with formation of complex connections (coordination number of silver – 2):

AgCl + _{2NH3 [Ag(NH3)2]} of Cl
_Ag2O + _4NH3 + _{H2O 2} [_Ag(NH3)2]OH

Ammoniac complexes of silver interact with aldehydes (silver mirror reaction):

	O II		O II
R –	With	+ [Ag(NH3)2]OH R–	With	+ Ag + NH3
	I H		I O	- NH4

Gold and its connections

Gold - is softer than Cu and Ag, ductile metal; easily forms the thinnest foil; noble metal, is steady both in dry, and in humid air. Let's dissolve only in mix of the concentrated hydrochloric and nitric acids ("nitrohydrochloric acid"):

Au + _HNO3 + 4HCl _H[AuCl4] + NO + _2H2O

Reacts with halogens when heating:

2Au + _{3Cl2 2AuCl3}

Connections are thermally not really steady and decay when heating with release of metal. Kompleksoobrazovatel (complexes of gold (III) possess coordination numbers 4, 5 and 6).

   

 

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