Chapter 3 - The Chemistry of Global Climate Change Flashcards

1
Q

What do greenhouse gases do?

A

absorb radiation/trap heat

ex. CO2, H2O, CH4

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2
Q

CO2

A

on the rise more now than 150 years ago (due to Industrial Revolution), earth’s temp has risen

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3
Q

What is the Greenhouse Effect?

A

process where gases trap heat –> heat stays and warms the planet

  • essential for life, planet would freeze otherwise (but too much = bad “enhanced greenhouse effect”)
  • energy return of over 80% –> increases earths temp
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4
Q

What is the history of our earth’s atmosphere in relation to climate?

A

early atmosphere: 1000x more CO2

bacteria used CO2 to make sugars

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5
Q

How do we know that the earth’s temp has increased?

A
  • core samples from ocean, bacteria remaining tells temp
  • magnetic alignment of earth
  • “heavy water” composition of ice
  • trapped bubbles tells concentration of ice when bubbles formed
  • all data seems to agree
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6
Q

Global Warming:

  1. Theory
  2. What’s possible…
  3. Fact
A

Theory: global warming is cased by an increase of CO2 and CH4 levels
Possible: increases in CO2 and CH4 levels are a result of warming, not a cause
Fact: CO2 and CH4 trap heat and contribute to global warming
–> cause or effect?

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7
Q

Recent evidence of global warming

A
  • atmospheric CO2 is increasing
  • global temps are increasing
  • -> biggest boom from Industrial Revolution
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8
Q

Other factors to global warming

A
  • orbital changes: temp maxima, major/minor ice ages
  • Airborne dust: volcanic activity
  • Cloud cover: weather patterns
  • Greenhouse gases
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9
Q

What is the outlook for the future?

A
In the past 100 years:
-CO2 conc. has increased 25%
-avg temp increased .5-.7 degrees C
Current:
-doubling the CO2 conc. --> 1.8-6.3 degree F increase
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10
Q

What are examples of greenhouse gases? what are not examples? Why the difference?

A

Examples: CO2, CH4, N2O, O3, H2O, CFCs
Not examples: O2, N2, Ar
Difference due to shape!

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11
Q

Bonds are made of ______

A

electrons

neg charge, repel each other

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12
Q

Molecular Shape: Tetrahedral

A

bonded atoms: 4

lone pairs: 0

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13
Q

Molecular Shape: Bent

A

bonded atoms: 2

lone pairs: 2 or 0

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14
Q

Molecular Shape: Trigonal Pyrimidal

A

bonded atoms: 3

lone pairs: 1

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15
Q

Molecular Shape: Trigonal Planar

A

bonded atoms: 3

lone pairs: 0

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16
Q

Molecular Shape: Linear

A

bonded atoms: 2

lone pairs: 0

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17
Q

Shape of a molecule determines ______

A

HOW a molecule can vibrate

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18
Q

Types of light

A

UVB/UVC –> bonds break

IR –> can’t break bonds (not enough energy), can cause vibration

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19
Q

How do you determine which wavelength?

A
  • can’t look at a molecule and determine wavelength

- bond strength and flexibility, atom masses

20
Q

What is symmetric stretching?

A
21
Q

What is asymmetric stretching?

A

—-><—-

22
Q

What are bending modes?

A

up/down OR diagonal

*need at least three atoms to bend (O2 can’t bend)

23
Q

Where does CO2 come from?

A

natural sources: respiration/photosynthesis

manmade sources: deforestation/burning fossil fuels

24
Q

Why are O2 and N2 not greenhouse gases?

A

they don’t absorb IR radiation

can’t vibrate = can’t trap heat

25
Q

What is the fossil fuel contribution to atmospheric CO2?

A

6-7 billion tons of carbon released

–> 1/2 goes into the atmosphere

26
Q

Increasing CO2 levels

A

Since 1860:
-concentration: 290-385ppm
-increases 1.5 ppm/year
excess CO2 = global warming = big concern

27
Q

How much does an atom weigh?

A

depends on the atom

28
Q

What is the standard for atomic weight?

A

one Carbon-12 = 12 amu

atomic mass = 12.01 (weighted average atomic mass for carbon –> no carbon atoms actually equal 12.01 amu)

29
Q

What does the 12 mean in Carbon-12?

A

mass #, total protons = neutrons

30
Q

Weighing Carbon

A

can’t weigh individual atoms
define in grams, not amu
–> 12g C contains 6.022 x 10^23 carbon atoms

31
Q

Conversions

A

grams—-(use molar mass)—–> moles —-(use Avagadro’s #)—–> atoms/molecules

32
Q

How many atoms are in .551g of K?

A

8.49 x 10^21 atoms K

33
Q

What is molecular mass (or molar mass)?

A

the sum of the atomic masses (in amu) in a molecule

–>mass of one mole of “anything” in grams

34
Q

What is the molecular mass of SO2? Molar mass?

A
  1. 07amu

64. 07g

35
Q

How many moles of C3H8O are in 72.5g?

A

1.2 moles

36
Q
  1. one mole of CO2 = ________

2. has molar mass of…..?

A
  1. 6.022 x 10^23 molecules CO2

2. 12.01 + 16 + 16 = 44.01 g

37
Q

What is a chemical reaction telling?

A

substances –> new substances

38
Q

What is a chemical equation telling?

A

reactants –> products

39
Q

How do you read this equation?

2Mg + O2 –> 2MgO

A
  1. two atoms Mg + one molecule O2 makes 2 MgO units
  2. two moles Mg + one mole O2 makes two moles MgO
  3. 48.6g Mg + 32g O2 makes 80.6g MgO
    NOT: 2g Mg + 1g O2 makes 2g MgO
40
Q

How to solve stoichiometry problems

A
  1. Balance chemical equation
  2. Convert to grams of known substances into moles
  3. Use coefficients - calculate # of moles unknown
  4. Convert moles to grams
41
Q

What is the Global Warming Potential (GWP)?

A

relative contribution of a molecule of an atmospheric gas to global warming

42
Q

Loss of Polar Ice Cap

A
  • year round sea ice in arctic is decreasing 9% per decade
  • ocean warms/ice melts –> more solar energy absorb by water creating pos feedbacks –> more ice melting
  • impacts water salinity, changes marine habitats, and widens shipping lanes (adds pollution)
43
Q

What is one way to reduce the severity of the greenhouse effect?

A

CO2 sequestration - take CO2 out of atmosphere and compress it

44
Q

Ozone Hole vs. Global Warming

A

Ozone Hole: O3, UV light, Montreal Agreement (US did sign)
Global Warming: CO2/CH4, IR radiation, Kyoto Protocol (US did not sign –> it charged each nation for CO2 emissions and US couldn’t scale back enough to not be fined)

45
Q

What is the enhanced greenhouse effect?

A

When atmospheric gases trap and return over 80% of the heat energy radiated by the earth

46
Q

What is global warming?

A

Increase in average global temps as a result of the enhanced greenhouse effect