| Date | November 2016 | Marks available | 3 | Reference code | 16N.3.sl.TZ0.13 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe and Suggest | Question number | 13 | Adapted from | N/A |
Question
Carbon dioxide and water vapour are greenhouse gases produced by the combustion of fossil fuels.
Explain the effect of the increasing concentration of atmospheric carbon dioxide on the acidity of oceans.
(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.
Markscheme
Any two of:
CO2 (g) CO2 (aq)
CO2 (aq) + H2O (l) H+ (aq) + HCO3– (aq)
OR
HCO3– AND H+ are formed «by dissolved CO2»
«increasing [CO2]» shifts equilibrium to right/increases acidity/decreases pH
H2O (l) not required over equilibrium sign for M1.
State symbols required in the equation in M1.
Accept “H2CO3 ” at either side of the equilibrium in M2.
Equilibrium sign required for M1 but not for M2.
i
bond length/C=O changes
OR
«asymmetric» stretching «of bonds»
OR
bond angle/OCO changes
Accept “molecule bends” for M1.
Accept appropriate diagrams
photon re-emitted in random direction
OR
polarity/dipole «moment» changes
OR
dipole «moment» created «when molecule absorbs IR»
ii
CO2 gas «ten times» more effective as greenhouse gas/GHG than H2O
OR
CO2 gas levels keep increasing «unlike H2O»
OR
CO2 has higher Global Warming Potential/GWP than H2O
OR
CO2 stays in the atmosphere for longer than H2O
Accept converse arguments.
Examiners report
Syllabus sections
- 17N.3.sl.TZ0.13d: Outline how water and carbon dioxide absorb infrared radiation.
-
18M.3.sl.TZ1.9a:
Identify one naturally occurring greenhouse gas, other than carbon dioxide or water vapour, and its natural source.
-
19M.3.hl.TZ1.15d(ii):
Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.
-
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.
-
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.
-
17M.3.sl.TZ1.17c:
Outline, giving the appropriate equation(s), how increasing levels of carbon dioxide will affect the pH of the oceans.
-
17M.3.sl.TZ2.14a:
Identify which region, A or B, corresponds to each type of radiation by completing the table.
-
19M.3.sl.TZ2.13a:
State one greenhouse gas, other than carbon dioxide.
-
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.
-
19M.3.sl.TZ1.11d(ii):
Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.
-
20N.3.hl.TZ0.11e(ii):
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
-
18M.3.sl.TZ2.11a:
Explain the molecular mechanism by which carbon dioxide acts as a greenhouse gas.
-
19M.3.sl.TZ1.11d(i):
Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.
-
18M.3.sl.TZ2.11b:
Discuss the significance of two greenhouse gases, other than carbon dioxide, in causing global warming or climate change.
-
19M.3.hl.TZ1.15d(i):
Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.
-
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.
-
18N.3.sl.TZ0.11e:
Explain, using an equation, the effect of increased carbon dioxide in the atmosphere on the pH of lake water.
-
16N.3.sl.TZ0.13a:
Explain the effect of the increasing concentration of atmospheric carbon dioxide on the acidity of oceans.
-
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.
-
19M.3.hl.TZ2.18b:
Outline one approach to controlling industrial emissions of carbon dioxide.
-
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.
-
19M.3.sl.TZ2.13c:
Outline one approach to controlling industrial emissions of carbon dioxide.
-
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.
-
19M.3.sl.TZ2.13b:
Describe the effect of infrared (IR) radiation on carbon dioxide molecules.
-
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.
-
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.
-
18M.3.sl.TZ1.9b:
Formulate an equation that shows how aqueous carbon dioxide produces hydrogen ions, H+(aq).
-
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.
-
20N.3.sl.TZ0.9f(ii):
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
