Chapter 3
The Chemistry of
Global Warming
Chemistry 1010
Dr. Harris
Suggested Problems



Emphasizing Essentials (pgs. 144 and
145): 2, 7, 9, 16, and 21.
Concentrating on Concepts (pg. 146): 33.
Exploring Extensions (pg. 147): 46.
3.1 In the Greenhouse

Jean-Baptiste Joseph Fourier (1768-1830)



John Tyndall (1820-1893)


French mathematician and physicist
Atmosphere and the glass of a “hothouse” or
greenhouse.
CO2 and H2O vapor absorb heat
Today



CO2 absorbs heat
Atmospheric CO2 concentration has increased over
the past 150 years
Earth’s avg. temp has not remained constant
3.2 The Testimony of Time

Photosynthesis


chlorophyll
6 CO2 + 6 H2O
100 million years ago
C6H12O6 + 6 O2
glucose
Estimated avg. temp 10-15ºC warmer than today
 CO2 concentration assumed to be considerably
higher

Figure 3.3
Notice the correlation between carbon dioxide and temp. change.
3.3 The Earth’s Energy Balance
Figure 3.4 – Look closely at the width of each arrow.
3.3 The Earth’s Energy Balance

Global Greenhouse Effect


Return of 84% of the energy radiated from the
surface of the Earth
Enhanced Greenhouse Effect

Energy return of greater than 84%
3.4 Molecules: How They Shape
Up




CO2, H2O, and CH4 are greenhouse
gases.
N2 and O2 are not greenhouse gases.
Why?
Answer comes from a closer look at the
molecular structure and shape.
3.4 Molecules: How They Shape
Up


Review of Lewis structures for N2 and O2
How about methane’s structure?




Let’s look at four different molecular structures
(methane, ammonia, water, and carbon dioxide).


Determine # of outer electrons associated with each
atom in the molecule.
Remember the octet rule when drawing the molecule.
Most stable molecular shape – bonding and
nonbonding electrons are as far from each other as
possible.
Remember structure names and bond angles.
Question 11
3.5 Vibrating Molecules and the
Greenhouse Effect
Figure 3.13 – Molecular vibrations in carbon dioxide.
3.5 Vibrating Molecules and the
Greenhouse Effect
Figure 3.16 – Molecular response to types of radiation.
3.5 Vibrating Molecules and the
Greenhouse Effect
Figure 3.14
Question 12
3.6 The Carbon Cycle:
Contributions from Nature and
Humans




6.0-8.2 Gt – amount of carbon dioxide
released by human activities
(deforestation/burning fossil fuels) per
year.
About ½ of this carbon dioxide is recycled
into the oceans and biosphere.
3.1-3.5 Gt increase of carbon per year.
Question 23 - Interesting
3.7 Weighing the Unweighable



Atomic mass – average mass of an atom
of that element as compared to an atomic
mass of exactly 12 amu for carbon-12.
1 amu = 1.66 x 10-24 g.
Notice that the mass number for carbon is
12.01.

The “.01” comes from the contribution of the
carbon-13 and carbon-14.
Question 18
3.7 Weighing the Unweighable

Let’s take a closer look at a laboratory scale.

Can only read to 0.1 mg.
Atomic Mass – can also be defined as the mass
(g) of the same number of atoms that are found
in exactly 12 g of
carbon-12.
 # carbon-12 atoms in exactly 12 g =
6.02 x 1023 (Avogadro’s #)
One Avogadro’s # of oxygen atoms = 16.00 g.

3.8 Of Molecules and Moles

Chemists usually don’t work with single atoms or
molecules.


Mole – Avogadro’s number of anything.



We need a chemist’s dozen.
You can think of the “mole” as the chemist’s dozen.
C + O2
CO2
Molar mass – mass of one Avogadro’s number
of specified particles.

Molar mass of carbon atoms = 12.0 g.
3.8 Of Molecules and Moles

Molar mass CO2 = (1 x molar mass C) +
(2 x molar mass O) = 44.0 g/mole
3.9 Manipulating Moles and Mass
with Math



Question – what mass of carbon dioxide
contains 3.3 Gt of carbon?
What mass units do you want to use?
Let’s work this out to the mass units that
you as a class select.
3.12 Has the Greenhouse Effect
Already Started?
Figure 3.24
3.12 Has the Greenhouse Effect
Already Started?

Status of text knowledge


Guided by 2001 report from the
Intergovernmental Panel on Climate Change
(IPCC).
Definitely true:
CO2 contributes to an elevated global
temperature.
 CO2 concentration in the atmosphere has
been increasing over the past century.

3.12 Has the Greenhouse Effect
Already Started?

Very likely:


Virtually certain:


The increase in CO2 concentration in the atmosphere
over the past century is a consequence of human
activity.
Average global temperature has increased during the
past century.
May be true:

CO2 and other gases generated by human activity are
responsible for this temperature increase.
3.12 Has the Greenhouse Effect
Already Started?

Uncertain:

The average global temperature will continue
to increase as anthropogenic emissions of
greenhouse gases increase.
3.15 Global Warming and Ozone
Depletion
End of Chapter 3