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Ch.18 - Chemistry of the Environment
All textbooksBrown 15th EditionCh.18 - Chemistry of the EnvironmentProblem 24
Chapter 18, Problem 24

Draw the Lewis structure for the chlorofluorocarbon CFC-11, CFCl3. What chemical characteristics of this substance allow it to effectively deplete stratospheric ozone?

Verified step by step guidance
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Step 1: Identify the total number of valence electrons in CFCl3. Carbon (C) has 4 valence electrons, fluorine (F) has 7, and each chlorine (Cl) has 7. Add these together to find the total number of valence electrons.
Step 2: Place the carbon atom in the center as it is the least electronegative element. Arrange the fluorine and three chlorine atoms around the carbon atom.
Step 3: Connect each of the surrounding atoms (F and Cl) to the central carbon atom using single bonds. Each single bond represents a pair of shared electrons.
Step 4: Distribute the remaining valence electrons to complete the octets of the fluorine and chlorine atoms. Each atom should have a total of 8 electrons in its valence shell, including the shared electrons in bonds.
Step 5: Verify that all atoms have complete octets and that the total number of electrons used matches the total number of valence electrons calculated in Step 1. Discuss how the presence of chlorine atoms in CFC-11 contributes to ozone depletion by releasing chlorine radicals in the stratosphere, which catalyze the breakdown of ozone molecules.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They help visualize the arrangement of electrons and the connectivity of atoms, which is crucial for understanding molecular geometry and reactivity. In the case of CFC-11 (CFCl3), drawing its Lewis structure reveals the distribution of electrons around the carbon, fluorine, and chlorine atoms.
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Chlorofluorocarbons (CFCs)

Chlorofluorocarbons are a class of compounds that contain carbon, chlorine, and fluorine. They are known for their stability and non-flammability, which made them popular as refrigerants and propellants. However, their stability also means they can persist in the atmosphere, leading to the release of chlorine atoms that catalyze the breakdown of ozone in the stratosphere, contributing to ozone depletion.

Ozone Depletion Mechanism

Ozone depletion occurs when ozone (O3) in the stratosphere is broken down by reactive species, such as chlorine atoms released from CFCs. When CFCs are exposed to ultraviolet (UV) radiation, they release chlorine, which can react with ozone, converting it into oxygen (O2) and significantly reducing the ozone layer's ability to absorb harmful UV radiation. This process highlights the environmental impact of CFCs and the importance of regulating their use.
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Related Practice
Textbook Question

Which of the following reactions in the stratosphere cause an increase in temperature there? (a) O(g) + O2(g) → O3+(g) (b) O3*(g) + M(g) → O3(g) + M*(g) (c) O2(g) + hv → 2 O(g) (d) O(g) + N2(g) → NO(g) + N(g) (e) All of the above

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Textbook Question

(a) What is the difference between chlorofluorocarbons and hydrofluorocarbons?

Textbook Question

(a) When chlorine atoms react with atmospheric ozone, what are the products of the reaction?

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Textbook Question

(b) Based on average bond enthalpies, would you expect a photon capable of dissociating a C-Cl bond to have sufficient energy to dissociate a C-Br bond?