The nature and refining method of elemental element of zinc subgroup

15.
4.
1 The nature of the element

An important feature of zinc subgroup elements is that they have low melting and boiling points
.

Compared with copper subgroup elements, zinc subgroup elements have fewer single electrons in the outer layer and weak metal bonds; compared with transition metal elements, zinc subgroup elements have full d orbitals in the secondary outer layer, with larger radius and weak metal bonds

Mercury is a liquid at room temperature, and has a very uniform volume expansion coefficient at -20 to 300°C, and does not wet glass, so it is often used in thermometers to indicate temperature
.

Mercury is volatile and the vapor is toxic.
Pay attention to laboratory ventilation when using it
.

If you accidentally spill the mercury, collect it as soon as possible, and then sprinkle sulfur powder on the place where there is metallic mercury to convert the mercury into HgS

Mercury can dissolve other metals to form amalgam
.

Due to the different composition, amalgam can be in two forms, liquid and solid

The d orbitals of the secondary outer layer of zinc subgroup elements are fully filled, and the d orbital electrons are not easy to participate in the bond formation, often forming compounds with oxidation number +2
.

However, compounds with a mercury oxidation number of +1 are stable

Zinc and cadmium are active metals that can replace hydrogen from dilute acid, while mercury is an inert metal
.

Pure zinc reacts very slowly with dilute acid, which may be caused by a large overpotential when hydrogen is precipitated on the surface of zinc

Excessive nitric acid dissolves mercury to produce mercury nitrate
.

3Hg+8HNO ₃ =3Hg(NO ₃ ) ₂ +2NO+4H ₂ O

But the excess mercury reacts with dilute nitric acid to obtain mercurous nitrate
.

6Hg +8HNO ₃ =3Hg ₂ (NO ₃ ) ₂ +2NO+4H ₂ O

Unlike cadmium and mercury, zinc is an amphoteric metal
.

Zinc can be dissolved in strong alkali solution and also in ammonia water

15.

4.

1.
Smelting of zinc

The flotation sphalerite is converted into zinc oxide by sintering
.

2ZnS+3O ₂ =2ZnO+2SO

Then the zinc oxide and coke are mixed and heated in a blast furnace to distill the resulting zinc out, and after cooling, crude zinc is obtained
.

2C+O ₂ =2CO

ZnO+CO=Zn+CO ₂

By removing impurities such as lead, cadmium, copper, and iron through rectification, zinc with a purity of 99.
9% can be obtained
.

To obtain purer metallic zinc, "hydrometallurgy" can be used
.

After zinc oxide and a small amount of sulfide was calcined with dilute sulfuric acid leach, a ZnO into ZnS04 .

2.
Treatment and refining of mercury

The HgS is calcined in an air stream at a temperature of 600°C to obtain elemental mercury
.

HgS+O ₂ =Hg+SO ₂

Iron or quicklime is calcined with HgS to obtain elemental mercury
.

HgS+Fe=Hg+FeS

4HgS+4CaO=4Hg+3CaS+CaSO ₄