Ozone

Ozone

An allotrope of oxygen consisting of molecules containing three oxygen atoms.

Allotrope

Ozone is described as an _________ of oxygen because O₂ and O₃ are different structural forms of the same element.

Three

How many oxygen atoms are present in one ozone molecule?

Bent

The molecular geometry of ozone (O₃) is ______.

Resonance

What concept is necessary to properly describe the bonding in an ozone molecule?

Two equivalent resonance structures

How many equivalent resonance structures are commonly used to represent the bonding in O₃?

Dry Oxygen

Ozone can be produced when __________ is passed between two electrically charged plates.

Electrical Discharge

The energy needed to convert O₂ into O₃ can be supplied by an __________.

Electrical Discharge, Heat, and Ultraviolet Light

Name the three energy sources mentioned that can promote the formation of ozone from oxygen.

3O₂(g) → 2O₃(g)

Chemical equation for the formation of ozone from molecular oxygen.

Endothermic Reaction

Is the formation of ozone from molecular oxygen endothermic or exothermic?

+287 kJ

The standard enthalpy change, ΔH°, for 3O₂(g) → 2O₃(g) is approximately ______.

Ozone

The characteristic sharp odor sometimes associated with sparking electrical equipment is due, in part, to ______.

Ultraviolet Light from the Sun

Ozone forms naturally in the upper atmosphere through the action of __________ on oxygen.

Stratosphere

Most atmospheric ozone occurs in this layer of Earth's atmosphere.

About 10 to 50 km

The stratospheric region discussed in the lesson extends approximately _____ above Earth's surface.

Absorbing Harmful Ultraviolet Light

How does stratospheric ozone help protect life on Earth?

O₃(g) → O(g) + O₂(g)

Chemical equation showing the decomposition of ozone caused by ultraviolet light.

Chemical Decomposition

Ozone absorbs harmful ultraviolet radiation from the Sun through what type of reaction?

Atomic Oxygen and Molecular Oxygen

What two products form when ozone undergoes photochemical decomposition? O₃ → _____ + _____.

O(g)

The reactive oxygen species produced when ultraviolet light decomposes O₃ into O₂ and another species.

Recombines with Molecular Oxygen

What happens to reactive atomic oxygen after ozone decomposes as part of the natural ozone cycle?

Ozone Cycle

The continuing formation, UV-induced decomposition, and reformation of atmospheric ozone is called the __________.

Stratospheric Ozone

Which type of atmospheric ozone helps protect organisms from harmful ultraviolet radiation?

Tropospheric Ozone

Which type of atmospheric ozone is considered a harmful pollutant?

Skin Cancer and Other UV Damage

Stratospheric ozone helps decrease the frequency of what harmful biological effects by reducing exposure to ultraviolet radiation?

Chlorofluorocarbons (CFCs)

These compounds, historically used as aerosol propellants and refrigerants, contributed significantly to depletion of stratospheric ozone.

Freons

Chlorofluorocarbons (CFCs) were commercially known by this name.

Ultraviolet Light

What causes CFC molecules in the stratosphere to decompose and release reactive chlorine?

Atomic Chlorine

Ultraviolet decomposition of CFCs produces this species, which reacts with ozone and contributes to its destruction.

Because chlorine atoms react with ozone molecules, causing a net removal of O₃ from the stratosphere.

Why did CFC emissions contribute to depletion of the ozone layer?

Ozone Depletion

The net removal of O₃ molecules from the stratosphere due to processes such as reactions involving chlorine atoms is known as __________.

Photochemical Smog

Tropospheric ozone is a toxic component of __________.

Stratosphere, Troposphere

Fill in the blanks: Ozone in the __________ helps protect us from UV radiation, whereas ozone in the __________ is a harmful pollutant.

Beneficial

Generally speaking, is stratospheric ozone beneficial or harmful to humans?

Harmful

Generally speaking, is tropospheric ozone beneficial or harmful to humans?

Bleaching Agent

Ozone can be used as a __________ for oils, waxes, fabrics, and starch.

By oxidizing colored compounds into colorless compounds.

How does ozone act as a bleaching agent?

Water Disinfectant

Ozone can be used as an alternative to chlorine for this water-treatment purpose.

Its High Reactivity

Why is ozone useful for applications such as bleaching and water disinfection?