Instruction

1

**The degree**

**of oxidation**is written above the symbol of the element, the stitch sign is placed, and then the value. It can be negative, positive or equal to zero. The sum of all degrees

**of oxidation**in the substance is equal to zero. Some substances have a constant degree

**of oxidation**for all compounds. For example, in metals it is always positive and equal to their valency (ability to attach or to replace a certain number of atoms or groups of atoms). The alkali metals have a degree

**of oxidation of**+1, while alkaline earth is +2. Hydrogen always has a degree

**of oxidation of**+1, except the hydrides, there is -1 (for example, KH(-1)).

**The degree**

**of oxidation**of the oxygen equal to -2 exceptions: peroxide (BaO2(-1)) and fluoride oxygen(O(+2)F). Fluorine always has -1(DQ(-1)).

2

If the substance consists of one or more atoms of the same name, i.e. it is simple, its degree

**of oxidation**equal to zero. For example, H2, Ag, O2, Na, etc.3

Complex substance in the first place set value of the degree

**of oxidation**of the elements, which it is not changed. Then we make an equation with one unknown, i.e. the degree of**oxidation**that you need to find, denoted by X. for Solve this equation, we obtain the desired value. It should be noted that in the presence of a complex substance of several atoms of the same element, the degree**of oxidation**in the preparation of the equations is multiplied by the number of items. Consider the examples.4

If you need to find the degree

**of oxidation**of sulphur in the substance Na2SO4 doing so: first, we arrange the known values are Na(+1)2SO(-2)4. We denote the degree**of oxidation**of sulfur for X, we write the equation, remembering about the fact that the sum of all the degree**of oxidation**is always zero: 2+X-8 = 0. Solve: X = 8-2 = +6. Therefore, the degree**of oxidation**of sulfur is +6.5

Another example: AgNO3. Place: Ag(+1)NO(-2)3. We obtain the equation: 1+X-6 = 0. Calculated: X = 6-1 = +5. The desired value is found.

Note

The degree of oxidation can have fractional values, for example in magnetic iron ore Fe2O3 is +8/3.