Posted by Bret on Friday, March 16, 2007 at 10:44am.
what is the oxidation number for nitrogen in the following?
NH3
NO2 1-
N2
NO2Cl
N2H4
For Further Reading
chemistry - bobpursley, Friday, March 16, 2007 at 11:26am
We will be happy to critique your thinking or work.
chemistry - Bret, Friday, March 16, 2007 at 11:37am
I don't even have a clue as to how to work it out.
You have seven rules for assigning oxidation numbers: memorize and use them.
http://chemistry.about.com/od/generalchemistry/a/oxidationno.htm
To determine the oxidation number for nitrogen in each compound, you can use the following rules:
1. The oxidation number of an element in its elemental form is always 0. Therefore, for N2, the oxidation number of nitrogen is 0.
2. In most compounds, the oxidation number of Group 1 elements is +1 and Group 2 elements is +2. However, in compounds with more electronegative elements, such as nitrogen, the Group 1 and Group 2 elements have oxidation numbers of -1 and -2, respectively. Therefore, for NH3, the oxidation number of nitrogen is -3.
3. The sum of the oxidation numbers of all the atoms in a neutral compound is 0. Since NH3 is a neutral compound and hydrogen has an oxidation number of +1, the oxidation number of nitrogen must be -3.
4. In polyatomic ions, the sum of the oxidation numbers of all the atoms is equal to the charge of the ion. For NO2^1-, the overall charge is -1. Let x be the oxidation number of nitrogen. By assigning -2 to each oxygen atom and -1 to the charge, we can set up the equation: x + 2(-2) = -1. Solving for x gives x = +4.
5. The oxidation number of oxygen in most compounds is -2. Using this rule, we can determine the oxidation number of nitrogen in NO2Cl. Let x be the oxidation number of nitrogen. By assigning -2 to each oxygen atom, -1 to the chlorine atom, and 0 to the overall charge, we can set up the equation: x + 2(-2) + (-1) + 0 = 0. Solving for x gives x = +4.
6. Hydrogen typically has an oxidation number of +1, except in metal hydrides where it has an oxidation number of -1. For N2H4, let x be the oxidation number of nitrogen. Since hydrogen has an oxidation number of +1, we can set up the equation: 2x + 4(+1) = 0. Solving for x gives x = -2.
By following these rules, you can determine the oxidation number of nitrogen in each compound. It's important to note that these rules provide a general guide, but there may be exceptions and variations depending on the specific compound.