degree oxidation written above the symbol element, Stitch is put a sign, and then the value.It may be negative, positive or zero.The sum of all the degrees of oxidation in matter is equal to zero.Some substances have a constant degree of oxidation at all joints.For example, a metal, it is always positive and equal to the valence of (ability to attach or replace a certain number of atoms or groups of atoms).Alkali metals have a degree of oxidation +1, and alkaline earth - two.Hydrogen always has an oxidation degree +1, except hydrides are there - -1 (eg, KH (-1)). degree oxidation of oxygen is -2, exceptions peroxides (BaO2 (-1)) and fluoride oxygen (O (+2) F)
.Fluorine is always -1 (NaF (-1)).
If a substance consists of one or more atoms of the same name, that is,is prime, then its degree of oxidation zero.For example, H2, Ag, O2, Na, etc.
In a complex matter in the first place we place value of the degree of oxidation have elements that have not changed it.Then we draw up an equation with one unknown, iethe degree of oxidation , you want to find, for denoted X. Solving this equation, we obtain the desired value.It should be noted that in the presence of complex substances more atoms of the same element of its degree of oxidation in the preparation of the equation is multiplied by the number of elements.Consider the following examples.
If necessary, find the degree oxidation of sulfur in the material Na2SO4 proceed as follows: first we arrange the known values: Na (+1) 2SO (-2) 4.Indicates the degree of oxidation sulfur for X, we write the equation, remembering about the fact that the sum of the degree of oxidation always zero: 2 + X-8 = 0 Solve: X = 8-2 = +6.Therefore, the degree of oxidation sulfur is six.
Another example: AgNO3.We arrange: Ag (+1) NO (-2) 3.We get the equation: 1 + X-6 = 0. We compute: X = 6-1 = +5.The desired value is found.
degree of oxidation can have fractional values, such as magnetite Fe2O3 is +8/3.
- "Handbook of Chemistry", GPKhomchenko, 2005.