Question 23M.3.SL.TZ1.11
| Date | May 2023 | Marks available | [Maximum mark: 7] | Reference code | 23M.3.SL.TZ1.11 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Calculate, Estimate, Outline, Suggest | Question number | 11 | Adapted from | N/A |
Energy production often has associated costs.
Calculate the mass of CO2 produced per 1000 kJ of heat obtained from the combustion of ethanol. Use section 13 of the data booklet.
[2]
«1000/1367=» 0.7315 «mol ethanol» ✓
«C2H6O + 3O2 → 2CO2 + 3H2O / each ethanol forms two carbon dioxides»
«0.7315 × 2 × 44.01 g mol−1 = »64 «g» ✓
Award [2] for correct final answer.
Global warming potential (GWP) is a measure of heat absorbed by a greenhouse gas relative to the heat absorbed by the same mass of carbon dioxide.
Suggest one piece of evidence, other than temperature rise, that shows correlation between greenhouse gas emission and global warming.
[1]
glacier/ice sheets/ retreat/melting
OR
rising sea levels ✓
Accept other reasonable answers, e.g. ocean acidification, severe weather patterns.
Do not accept just ‘climate change’.
Outline how greenhouse gas molecules absorb infrared radiation.
[1]
«increase in bond» stretching/vibrating/bending
OR
bond angles/lengths change ✓
Accept dipole moment changes.
Accept light energy is converted into mechanical/potential/internal energy of the molecule.
The GWP of methane is approximately 21. Estimate the heat absorbed by one mole of methane relative to a mole of carbon dioxide.
[2]
«Mr CH4: Mr CO2/ 16.05 ÷ 44.01 =» 0.365 ✓
«21 × 0.365 = » 7.66 «times» ✓
Award [2] for correct final answer.
Accept 7.64 «times» (integer Mrs).
Award [1 max] for 57.6 «times» if inverted ratio is used.
Suggest, giving one reason, whether the use of biofuels or nuclear power has a lower carbon footprint.
[1]
biofuels AND CO2 emission involved in mining/refining nuclear fuel
OR
nuclear AND no CO2 emitted directly/from fuel. ✓
Accept biofuels AND plants/crops remove CO2 from atmosphere.
Accept other valid reasoning.