Question 19N.3.sl.TZ0.14
| Date | November 2019 | Marks available | [Maximum mark: 6] | Reference code | 19N.3.sl.TZ0.14 |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Explain, Formulate, Outline, State | Question number | 14 | Adapted from | N/A |
Ethanol is a biofuel that can be mixed with gasoline.
Write the equation for the complete combustion of ethanol.
[1]
C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l) ✔
Outline the evidence that relates global warming to increasing concentrations of greenhouse gases in the atmosphere.
[2]
Any two of:
«showing strong» correlation between «atmospheric» CO2 concentration/greenhouse gas concentration and average «global/surface/ocean» temperature ✔
lab evidence that greenhouse gases/CO2 absorb(s) infrared radiation ✔
«advanced» computer modelling ✔
ice core data ✔
tree ring data ✔
ocean sediments / coral reefs / sedimentary rocks data ✔
NOTE: Do not accept “global warming” for “average temperature”.
Do not accept “traps/reflects heat” OR “thermal energy”.
Evidence must be outlined and connected to data.
Accept references to other valid greenhouse gases other than carbon dioxide/CO2, such as methane/CH4 or nitrous oxide/N2O.
Explain, including a suitable equation, why biofuels are considered to be carbon neutral.
[2]
biofuel raw material/sugar/glucose formed by photosynthesis
OR
biofuel raw material/sugar/glucose uses up carbon dioxide during its formation
OR
biofuel from capturing gases due to decaying organic matter formed from photosynthesis ✔
6CO2 (g) + 6H2O (l) → C6H12O6 (aq) + 6O2 (g) ✔
NOTE: Accept arguments based on material coming from plant sources consuming carbon dioxide/carbon for M1.
State the type of reaction that occurs when ethanol reacts with vegetable oil to form biodiesel.
[1]
transesterification
OR
«nucleophilic» substitution/SN ✔