Chapter 3Chapter 3The Chemistry of The Chemistry of Global WarmingGlobal Warming

Chemistry 1010Chemistry 1010

Dr. HarrisDr. Harris

Suggested ProblemsSuggested Problems

Emphasizing Essentials (pgs. 144 and Emphasizing Essentials (pgs. 144 and 145): 2, 7, 9, 16, and 21.145): 2, 7, 9, 16, and 21.

Concentrating on Concepts (pg. 146): 33.Concentrating on Concepts (pg. 146): 33. Exploring Extensions (pg. 147): 46.Exploring Extensions (pg. 147): 46.

3.1 In the Greenhouse3.1 In the Greenhouse

Jean-Baptiste Joseph Fourier (1768-1830)Jean-Baptiste Joseph Fourier (1768-1830) French mathematician and physicistFrench mathematician and physicist Atmosphere and the glass of a “hothouse” or Atmosphere and the glass of a “hothouse” or

greenhouse.greenhouse. John Tyndall (1820-1893)John Tyndall (1820-1893)

COCO22 and H and H22O vapor absorb heatO vapor absorb heat TodayToday

COCO22 absorbs heat absorbs heat Atmospheric COAtmospheric CO22 concentration has increased over concentration has increased over

the past 150 yearsthe past 150 years Earth’s avg. temp has not remained constantEarth’s avg. temp has not remained constant

3.2 The Testimony of Time3.2 The Testimony of Time

PhotosynthesisPhotosynthesis 6 CO6 CO22 + 6 H + 6 H22O CO C66HH1212OO66 + 6 O + 6 O22

100 million years ago100 million years ago Estimated avg. temp 10-15Estimated avg. temp 10-15ºC warmer than todayºC warmer than today COCO22 concentration assumed to be considerably concentration assumed to be considerably

higherhigher

chlorophyll

glucose

Figure 3.3Figure 3.3

Notice the correlation between carbon dioxide and temp. change.

3.3 The Earth’s Energy Balance3.3 The Earth’s Energy Balance

Figure 3.4 – Look closely at the width of each arrow.

3.3 The Earth’s Energy Balance3.3 The Earth’s Energy Balance

Global Greenhouse EffectGlobal Greenhouse Effect Return of 84% of the energy radiated from the Return of 84% of the energy radiated from the

surface of the Earthsurface of the Earth Enhanced Greenhouse EffectEnhanced Greenhouse Effect

Energy return of greater than 84%Energy return of greater than 84%

3.4 Molecules: How They Shape 3.4 Molecules: How They Shape UpUp

COCO22, H, H22O, and CHO, and CH44 are greenhouse are greenhouse

gases.gases. NN22 and O and O22 are not greenhouse gases. are not greenhouse gases. Why?Why? Answer comes from a closer look at the Answer comes from a closer look at the

molecular structure and shape.molecular structure and shape.

3.4 Molecules: How They Shape 3.4 Molecules: How They Shape UpUp

Review of Lewis structures for NReview of Lewis structures for N22 and O and O22 How about methane’s structure?How about methane’s structure?

Determine # of outer electrons associated with each Determine # of outer electrons associated with each atom in the molecule.atom in the molecule.

Remember the octet rule when drawing the molecule.Remember the octet rule when drawing the molecule. Most stable molecular shape – bonding and Most stable molecular shape – bonding and

nonbonding electrons are as far from each other as nonbonding electrons are as far from each other as possible.possible.

Let’s look at four different molecular structures Let’s look at four different molecular structures (methane, ammonia, water, and carbon dioxide).(methane, ammonia, water, and carbon dioxide). Remember structure names and bond angles.Remember structure names and bond angles.

Question 11Question 11

3.5 Vibrating Molecules and the 3.5 Vibrating Molecules and the Greenhouse EffectGreenhouse Effect

Figure 3.13 – Molecular vibrations in carbon dioxide.

3.5 Vibrating Molecules and the 3.5 Vibrating Molecules and the Greenhouse EffectGreenhouse Effect

Figure 3.16 – Molecular response to types of radiation.

3.5 Vibrating Molecules and the 3.5 Vibrating Molecules and the Greenhouse EffectGreenhouse Effect

Figure 3.14Question 12

3.6 The Carbon Cycle: 3.6 The Carbon Cycle: Contributions from Nature and Contributions from Nature and

HumansHumans 6.0-8.2 Gt – amount of carbon dioxide 6.0-8.2 Gt – amount of carbon dioxide

released by human activities released by human activities (deforestation/burning fossil fuels) per (deforestation/burning fossil fuels) per year.year.

About ½ of this carbon dioxide is recycled About ½ of this carbon dioxide is recycled into the oceans and biosphere.into the oceans and biosphere.

3.1-3.5 Gt increase of carbon per year.3.1-3.5 Gt increase of carbon per year. Question 23 - InterestingQuestion 23 - Interesting

3.7 Weighing the Unweighable3.7 Weighing the Unweighable

Atomic mass – average mass of an atom Atomic mass – average mass of an atom of that element as compared to an atomic of that element as compared to an atomic mass of exactly 12 amu for carbon-12.mass of exactly 12 amu for carbon-12.

1 amu = 1.66 x 101 amu = 1.66 x 10-24-24 g. g. Notice that the mass number for carbon is Notice that the mass number for carbon is

12.01.12.01. The “.01” comes from the contribution of the The “.01” comes from the contribution of the

carbon-13 and carbon-14.carbon-13 and carbon-14.

Question 18

3.7 Weighing the Unweighable3.7 Weighing the Unweighable

Let’s take a closer look at a laboratory scale.Let’s take a closer look at a laboratory scale. Can only read to 0.1 mg.Can only read to 0.1 mg.

Atomic Mass – can also be defined as the mass Atomic Mass – can also be defined as the mass (g) of the same number of atoms that are found (g) of the same number of atoms that are found in exactly 12 g of in exactly 12 g of

carbon-12.carbon-12. # carbon-12 atoms in exactly 12 g = # carbon-12 atoms in exactly 12 g =

6.02 x 106.02 x 102323 (Avogadro’s #) (Avogadro’s #)

One Avogadro’s # of oxygen atoms = 16.00 g.One Avogadro’s # of oxygen atoms = 16.00 g.

3.8 Of Molecules and Moles3.8 Of Molecules and Moles

Chemists usually don’t work with single atoms or Chemists usually don’t work with single atoms or molecules.molecules. We need a chemist’s dozen.We need a chemist’s dozen.

Mole – Avogadro’s number of anything. Mole – Avogadro’s number of anything. You can think of the “mole” as the chemist’s dozen.You can think of the “mole” as the chemist’s dozen.

C + OC + O22 CO CO22

Molar mass – mass of one Avogadro’s number Molar mass – mass of one Avogadro’s number of specified particles.of specified particles. Molar mass of carbon atoms = 12.0 g.Molar mass of carbon atoms = 12.0 g.

3.8 Of Molecules and Moles3.8 Of Molecules and Moles

Molar mass COMolar mass CO22 = (1 x molar mass C) + = (1 x molar mass C) +

(2 x molar mass O) = 44.0 g/mole(2 x molar mass O) = 44.0 g/mole

3.9 Manipulating Moles and Mass 3.9 Manipulating Moles and Mass with Mathwith Math

Question – what mass of carbon dioxide Question – what mass of carbon dioxide contains 3.3 Gt of carbon?contains 3.3 Gt of carbon?

What mass units do you want to use?What mass units do you want to use? Let’s work this out to the mass units that Let’s work this out to the mass units that

you as a class select.you as a class select.

3.12 Has the Greenhouse Effect 3.12 Has the Greenhouse Effect Already Started?Already Started?

Figure 3.24

3.12 Has the Greenhouse Effect 3.12 Has the Greenhouse Effect Already Started?Already Started?

Status of text knowledgeStatus of text knowledge Guided by 2001 report from the Guided by 2001 report from the

Intergovernmental Panel on Climate Change Intergovernmental Panel on Climate Change (IPCC).(IPCC).

Definitely true:Definitely true: COCO22 contributes to an elevated global contributes to an elevated global

temperature.temperature. COCO22 concentration in the atmosphere has concentration in the atmosphere has

been increasing over the past century.been increasing over the past century.

3.12 Has the Greenhouse Effect 3.12 Has the Greenhouse Effect Already Started?Already Started?

Very likely:Very likely: The increase in COThe increase in CO22 concentration in the atmosphere concentration in the atmosphere

over the past century is a consequence of human over the past century is a consequence of human activity.activity.

Virtually certain:Virtually certain: Average global temperature has increased during the Average global temperature has increased during the

past century.past century. May be true:May be true:

COCO22 and other gases generated by human activity are and other gases generated by human activity are

responsible for this temperature increase.responsible for this temperature increase.

3.12 Has the Greenhouse Effect 3.12 Has the Greenhouse Effect Already Started?Already Started?

Uncertain:Uncertain: The average global temperature will continue The average global temperature will continue

to increase as anthropogenic emissions of to increase as anthropogenic emissions of greenhouse gases increase.greenhouse gases increase.

3.15 Global Warming and Ozone 3.15 Global Warming and Ozone DepletionDepletion

End of Chapter 3End of Chapter 3