| Date | May 2018 | Marks available | 2 | Reference code | 18M.3.sl.TZ2.11 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Discuss | Question number | 11 | Adapted from | N/A |
Question
Carbon dioxide is a product of the combustion of petrol.
Explain the molecular mechanism by which carbon dioxide acts as a greenhouse gas.
Discuss the significance of two greenhouse gases, other than carbon dioxide, in causing global warming or climate change.
Markscheme
Any three of:
IR/long wavelength/low frequency radiation radiated/emitted by the Earth’s «surface absorbed in the bonds»
bond length/C=O changes
OR
«asymmetric» stretching of bonds
OR
bond angle/OCO changes
polarity/dipole «moment» changes
OR
dipole «moment» created «when molecule absorbs IR»
«some of» energy is then re-radiated towards «the surface of the» Earth
Do not accept terms such as “reflect” OR “bounced” OR “trapped”.
[3 marks]
Any two of:
H2O AND «relatively» greater abundance/stable concentration/less effective at absorbing radiation/lower GWP so not much overall effect on global warming/climate change
CH4/N2O/CFCs/SF6/O3/HCFCs AND more effective «than CO2» at absorbing radiation/higher GWP so could contribute to global warming/climate change
PFCs/SF6/NF3/Some CFCs AND have very long life in atmosphere so could contribute «in the future» to global warming/climate change
Accept names or formulas.
Accept two different gases with the same effect for [2].
Award [1 max] for identifying the names/formulas of two greenhouse gases.
Accept “greenhouse factor” for “GWP” but not just “greenhouse effect”.
For M3, do not allow “CFC” alone as only some have long lifetimes (eg, CFC-115, CFC-113).
[2 marks]
Examiners report
Syllabus sections
- 17N.3.sl.TZ0.13d: Outline how water and carbon dioxide absorb infrared radiation.
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18M.3.sl.TZ1.9a:
Identify one naturally occurring greenhouse gas, other than carbon dioxide or water vapour, and its natural source.
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19M.3.hl.TZ1.15d(ii):
Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.
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17M.3.sl.TZ1.17d:
Many combustion processes also release particulate matter into the atmosphere. Suggest, giving your reason, how this might affect the temperature of the Earth’s surface.
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18M.3.sl.TZ1.9c:
The concentrations of oxygen and nitrogen in the atmosphere are much greater than those of greenhouse gases. Outline why these gases do not absorb infrared radiation.
- 18N.3.hl.TZ0.14c: Contrast the importance of carbon dioxide and methane as greenhouse gases.
- 18N.3.sl.TZ0.11d: Contrast the importance of carbon dioxide and methane as greenhouse gases.
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17M.3.sl.TZ1.17c:
Outline, giving the appropriate equation(s), how increasing levels of carbon dioxide will affect the pH of the oceans.
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17M.3.sl.TZ2.14a:
Identify which region, A or B, corresponds to each type of radiation by completing the table.
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19M.3.sl.TZ2.13a:
State one greenhouse gas, other than carbon dioxide.
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17M.3.sl.TZ1.17a:
Suggest why it is only in recent years that specific predictions of the future effects of fossil fuel combustion have been made.
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19M.3.sl.TZ1.11d(ii):
Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.
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16N.3.sl.TZ0.13b:
(i) Describe the changes that occur at the molecular level when atmospheric carbon dioxide gas absorbs infrared radiation emitted from the Earth’s surface.
(ii) Other than changes to the acidity of oceans, suggest why the production of carbon dioxide is of greater concern than the production of water vapour.
-
20N.3.hl.TZ0.11e(ii):
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
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18M.3.sl.TZ2.11a:
Explain the molecular mechanism by which carbon dioxide acts as a greenhouse gas.
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19M.3.sl.TZ1.11d(i):
Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.
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19M.3.hl.TZ1.15d(i):
Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.
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17N.3.sl.TZ0.13c:
Climate change or global warming is a consequence of increased levels of carbon dioxide in the atmosphere. Explain how the greenhouse effect warms the surface of the earth.
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18N.3.sl.TZ0.11e:
Explain, using an equation, the effect of increased carbon dioxide in the atmosphere on the pH of lake water.
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16N.3.sl.TZ0.13a:
Explain the effect of the increasing concentration of atmospheric carbon dioxide on the acidity of oceans.
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18N.3.hl.TZ0.14d:
Explain, using an equation, the effect of increased carbon dioxide in the atmosphere on the pH of lake water.
-
19M.3.hl.TZ2.18a:
Describe the effect of infrared (IR) radiation on carbon dioxide molecules.
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19M.3.hl.TZ2.18b:
Outline one approach to controlling industrial emissions of carbon dioxide.
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17M.3.sl.TZ2.14b.ii:
Describe how large amounts of CO2 could reduce the pH of the ocean using an equation to support your answer.
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19M.3.sl.TZ2.13c:
Outline one approach to controlling industrial emissions of carbon dioxide.
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20N.3.hl.TZ0.11e(i):
When combusted, all three fuels can release carbon dioxide, a greenhouse gas, as well as particulates. Contrast how carbon dioxide and particulates interact with sunlight.
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19M.3.sl.TZ2.13b:
Describe the effect of infrared (IR) radiation on carbon dioxide molecules.
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20N.3.sl.TZ0.9f(i):
When combusted, all three fuels can release carbon dioxide, a greenhouse gas, as well as particulates. Contrast how carbon dioxide and particulates interact with sunlight.
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17M.3.sl.TZ1.17b:
Carbon dioxide has two different bond stretching modes illustrated below.
Predict, with an explanation, whether these stretching modes will absorb infrared radiation.
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18M.3.sl.TZ1.9b:
Formulate an equation that shows how aqueous carbon dioxide produces hydrogen ions, H+(aq).
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17M.3.sl.TZ2.14b.i:
Oceans can act as a carbon sink, removing some CO2(g) from the atmosphere.
CO2(g) CO2(aq)
Aqueous carbon dioxide, CO2(aq), quickly reacts with ocean water in a new equilibrium reaction. Construct the equilibrium equation for this reaction including state symbols.
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20N.3.sl.TZ0.9f(ii):
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
