The Foundations of Chemistry

organic groups (Sections 18-4 and 27-12). All involve sp^3 -hybridized N. All are weak bases

because of the unshared pair of electrons on N.

960 CHAPTER 24: Some Nonmetals and Metalloids

 3 
 5 
 1

Ammonia, NH 3 Methylamine, CH 3 NH 2 Dimethylamine, (CH 3 ) 2 NH Trimethylamine, (CH 3 ) 3

NITROGEN OXIDES

Nitrogen forms several oxides, in which it exhibits positive oxidation states of 1 to 5 (Table

24-8). All have positive free energies of formation, owing to the high dissociation energy

of N 2 and O 2 molecules. All are gases except N 2 O 5 , a solid that melts at 30.0°C.

Dinitrogen Oxide (
1 Oxidation State)

Molten ammonium nitrate undergoes autooxidation–reduction (decomposition) at 170 to

260°C to produce dinitrogen oxide, also called nitrous oxide.

heat

NH 4 NO 3 (
)888nN 2 O(g)
2H 2 O(g)
heat

At higher temperatures, explosions occur, producing N 2 , O 2 , and H 2 O.

heat

2NH 4 NO 3 (
)888n2N 2 (g)
O 2 (g)
4H 2 O(g)
heat

Dinitrogen oxide supports combustion because it produces O 2 when heated.

heat

2N 2 O(g)888n2N 2 (g)
O 2 (g)
heat

The molecule is linear but unsymmetrical, with a dipole moment of 0.17 D.

Nitrogen Oxide (
2 Oxidation State)

The first step of the Ostwald process (Section 24-16) for producing HNO 3 from NH 3 is

used for the commercial preparation of nitrogen oxide, NO.

catalyst

4NH 3 (g)
5O 2 (g)88888n 4NO(g)
6H 2 O(g)

heat

NO is not produced in large amounts in nature under usual conditions. It is formed by

direct reaction of N 2 and O 2 in electrical storms.

24-15

Some dentists use N 2 O for its mild
anesthetic properties. It is also known
as laughing gas because of its side
effects.

Dinitrogen oxide, or nitrous oxide,
N 2 O, mp 90.8°C, bp 88.8°C.