| Date | November 2018 | Marks available | 2 | Reference code | 18N.3.sl.TZ0.11 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Compare and contrast | Question number | 11 | Adapted from | N/A |
Question
Solar energy, which is freely available, is indispensable to life on earth.
Suggest another advantage and one disadvantage of solar energy.
Light can be absorbed by chlorophyll and other pigments.
Consider molecules A and B represented below.
Identify, with a reason, the molecule that absorbs visible light.
State a physical property of vegetable oils that makes them very difficult to use as fuel in internal combustion engines.
Describe how vegetable oils can be converted to a more suitable fuel.
Contrast the importance of carbon dioxide and methane as greenhouse gases.
Explain, using an equation, the effect of increased carbon dioxide in the atmosphere on the pH of lake water.
Markscheme
Advantage:
renewable «energy source»
OR
does not produce greenhouse gases
OR
can be installed «almost» anywhere
OR
low maintenance costs ✔
Disadvantage:
widely dispersed/not concentrated «form of energy»
OR
geography/weather/seasonal dependent
OR
not available at night
OR
energy storage is difficult/expensive
OR
toxic/hazardous materials used in production
OR
concerns about space/aesthetics/local environment where installed
OR
need to be «constantly» cleaned ✔
Accept “can be used for passive/active heating”, “can be converted to electric energy”.
Accept any specific greenhouse gas name or formula for “greenhouse gases”.
Accept “solar cells require large areas”, “solar cell manufacture produces pollution/greenhouse gases”, “higher cost of solar cells «compared with traditional sources such as fossil fuels or hydroelectric»”.
B AND larger/more extensive «electronic» conjugation
OR
B AND «contains» more alternate single and double bonds ✔
Accept more specific statements, such as “sp3 carbon in A prevents conjugation between aromatic rings”.
high viscosity ✔
Accept “low volatility”, just “viscous/viscosity” OR “does not flow easily”.
convert to esters of monoatomic alcohols
OR
react with short-chain alcohols «in the presence of acid or base» ✔
Accept “convert to shorter «carbon chain» esters” OR “transesterification”.
Accept specific alcohols, such as methanol or ethanol.
carbon dioxide/CO2 more/most abundant «GHG than methane/CH4»
OR
carbon dioxide/CO2 has «much» longer atmospheric life «than methane/CH4» ✔
methane/CH4 «much» better/more effective at absorbing IR radiation «than carbon dioxide/CO2»
OR
methane/CH4 has a greater greenhouse factor «than carbon dioxide/CO2»
OR
methane/CH4 has a greater global warming potential/GWP «than carbon dioxide/CO2» ✔
Accept “carbon dioxide/CO2 contributes more to global warming «than methane/CH4»”.
CO2 (g) + H2O (l) H+ (aq) + HCO3– (aq)
OR
CO2 (g) CO2 (aq) AND CO2 (aq) + H2O (l) H+ (aq) + HCO3– (aq) ✔
«increasing [CO2 (g)]» shifts equilibrium/reaction to right AND pH decreases ✔
Accept “H2CO3 (aq)” for “CO2 (aq) + H2O (l)”.
Equilibrium arrows required for M1.
State symbols required for CO2 (g) CO2 (aq) equation only for M1.
Accept “concentration of H+/[H+] increases AND pH decreases” for M2.
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.
-
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.
-
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.
-
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.
