what is an oxidation state?how do u calculate it?

Answer 1

In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. (http://en.wikipedia.org/wiki/Oxidation_state)

Use algebra.

MnO4 -
x + 4 (-2) = -1
x - 8 = -1
x= 7

Answer 2

Oxidation state is a somewhat arbitrary (in certain cases) value assigned to atoms in compounds that indicates how many electrons the atom has gained or lost in reduction-oxidation reactions.

For elements in their standard states, the oxidation state is always 0. So, Cu(s) and O2(g) have oxidation numbers of 0. For monoatomic ions, the oxidation state is the charge on the ion. So, Fe3+ has an oxidation state of +3, and Cl- has an oxidation state of -1.

For atoms in compounds, there are some basic rules that let you assign oxidation states to the other atoms. Your chemistry text will have a complete list of rules, but here are a few of them:

Oxygen in nearly all compounds has an oxidation state of -2. The only exception is when oxygen is in the form of peroxide, like in hydrogen peroxide H2O2. In that compound, each hydrogen is +1, so each of the oxygens has to be -1.

Hydrogen is nearly always +1, except when it is bound to to metals where it will be -1.

In a polyatomic ion, the sum of the oxidation numbers has to add up to the charge on the ion. So in a sulfate ion (SO42-) each oxygen is -2, so sulfur has to be +6.

Hope this helps...Read the section in your text on assigning oxidation numbers...

Answer 3

Oxidation state is a number assigned to an element in a compound according to some rules. This number enable us to describe oxidation-reduction reactions, and balancing redox chemical reactions. You are learning the skill to assign oxidation states (or oxidation numbers) to a variety of compounds and ions.