Презентация на тему Redox reactions

chemical reactions that occur with a change in the

oxidation state of the elements included in the reactants

atom, molecule or ion.
Atoms are converted into positively charged

ion: Zn0 – 2e → Zn2+
negatively charged ion becomes neutral atom: 2Cl- -2e →Cl20
S2- -2e →S0
The value of the positively charged ion (an atom) is increased accordingly the number of electron donating:
Fe2+ -1e →Fe3+
Mn+2 -2e →Mn+4

of electrons an atom, molecule or ion.

Atom converted to

a negatively charged ion
S0 + 2e → S2−
Br0 + e → Br −

The value of the positively charged ions (atoms)      reduced by the number of electrons attached:
Mn+7 + 5e → Mn+2
S+6 + 2e → S+4
− or it can go into a neutral atom:
Н+ + е → Н0
Cu2+ + 2e → Cu0

electrons. They are in the process redox reaction oxidized

Typical reductants:
● metal atoms with high atomic radii (I-A, II-A group), as well as Fe, Al, Zn
● simple substances, non-metals: hydrogen, carbon, boron;
● negative ions: Cl−, Br−, I−, S2−, N−3. We are reducing the fluoride ion F−.
● metal ions in lower oxidation states: Fe2+,Cu+,Mn2+,Cr3+;
● complex ions and molecules containing atoms with intermediate oxidation state: SO32−, NO2−; СО, MnO2 and others.

electrons join. They are in the process of oxidation-reduction

reactions are restored
Typical oxidizers:
● nonmetal atoms VII-A, VI-A, VA group consisting of simple substances
● metal ions in the higher oxidation state:
Cu2+, Fe3+,Ag+ …
● Complex ions and molecules containing atoms with the highest and lowest oxidation state:с.о.: SO42−, NO3−, MnO4−, СlО3−, Cr2O72-, SO3, MnO2 and others

the effect of such factors as the stability of

the molecule or ion. The stronger the particle, the less it shows the redox properties

reductant
2Н2S+3O2=2H2O+2SO2
S0,S+4O2 – oxidant and reductant
S+O2=SO2

2SO2+O2=2SO3 (reductant)
S+2Na=Na2S SO2+2H2S=3S+2H2O
(oxidant)
Н2S+6O4 - oxidant
Cu+2H2SO4=CuSO4+SO2+2H2O

of atoms of chemical elements in the simple substance

= 0
The algebraic sum of oxidation states of all elements in the ion is the ion charge
The algebraic sum of oxidation states of all elements in the composite material is 0.

K+1 Mn+7 O4-2

1+х+4(-2)=0

→ 2Al+3 Cl3-1
Intramolecular oxidation
2KCl+5O3-2 →2KCl-1 + 3O20
Disproportionation, dismutation (repair

itself, autoxidation):
3Cl20 + 6KOH (гор.) →KCl+5O3 +5KCl-1+3H2O
2N+4O2+ H2O →HN+3O2 + HN+5O3

common. They linked the metabolic processes in living organisms,

respiration, rotting, fermentation, photosynthesis.
Redox reactions provide the cycling of matter in nature. They can be seen from the combustion and smelting of metal corrosion. With their help prepared alkalis, acids and other valuable chemicals.
Redox reactions underlie energy conversion interacting chemicals in eclectic energy in the battery cell.

as a result of chemical and electrochemical interactions with

their environment.
This redox reaction in which the metal atoms become ions. The more active the metal, so it is more susceptible to corrosion.
In the role of an oxidant act atmospheric oxygen and hydrogen cations.

Carbon and sulfur gases contained in the atmosphere
Sea

water
Groundwater

as a result of their chemical interactions with the

substances of the environment.
The protective oxide film on the aluminum surface
Loose film on the iron surface, leading to destruction of metal

accompanied by the appearance of an electric current in

water or another electrolyte medium.
Chemical processes - this oxidation metal recoil electrons.
Electrical processes - transfer of electrons from one site to another product.

in a series of activity of metal: the farther

they are from each other, the faster corrosion.
The purity of the metal: the impurity accelerate corrosion. Irregularities in the metal surface cracks.
Ground water, sea water, the environment of the electrolyte.
Temperature increase.
The action of microorganisms (fungi, bacteria, lichens to metals with high corrosion resistance).

varnishes, enamels);
Covering other metals (gold-plated, silver, chrome, zinc

plating);
Creation and use of corrosion-resistant alloys Introduction to the inhibitors reduce aggressive environment;
Sacrificial protection