Ozone -- from Eric Weisstein's World of Chemistry

Inorganic Chemistry

Chemical Elements

Ozone

Ozone () is the form of oxygen consisting of three bound oxygen atoms. It is stable only in high-energy environments (such as near electric discharges). It can be formed by the reactions,

(1)

(2)

(3)

and depleted by

(4)

(5)

(6)

The Chapman stratospheric ozone theory assumes pure oxygen chemistry (no surface chemistry or catalysis) and photochemical equilibrium (no transport). Consider the following reactions, where M is an unspecified third species,

where , , and are rate constants and and are photodissociation constants given at 40 km altitude mid-latitude (250 K, 2.9 mbar). At this location, the concentrations of M and O₂ are

			(7)
			(8)

The destruction rates are


			(9)
			(10)

In equilibrium, [O₂] and [M] are constant. Therefore, define the following constants

			(11)
			(12)
			(13)

In equilibrium, (9) and (10) must be zero. Substituting the constants in then gives

			(14)
			(15)

Define odd oxygen by

(16)

then




			(17)

If we assume that recycling is much more rapid than net production and loss of O and O₃ in photochemical equilibrium

(18)

then (15) becomes

(19)

We know that . If we know assume that the major loss of O_x is by the second (and not third reaction), we can approximate (17) by

(20)

Dividing (19) by (20)

(21)


			(22)

Plugging the solution for [O₃] into (19) gives


			(23)