Question 19M.3.sl.TZ2.13
| Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.3.sl.TZ2.13 |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Describe, Outline, State | Question number | 13 | Adapted from | N/A |
This question is about global warming.
State one greenhouse gas, other than carbon dioxide.
[1]
Any one of:
methane, water, nitrous oxide/nitrogen(I) oxide, ozone, CFCs, sulfur hexafluoride [✔]
Note: Accept formulas.
Do not accept “NO2”, “NOx”, “oxides of sulfur”.
This question was well answered.
Describe the effect of infrared (IR) radiation on carbon dioxide molecules.
[2]
bond length/C=O distance changes
OR
«asymmetric» stretching «of bonds»
OR
bond angle/OCO changes [✔]
polarity/dipole «moment» changes
OR
dipole «moment» created «when molecule absorbs IR» [✔]
Note: Accept appropriate diagrams.
This question was fairly well answered with most students receiving one of the two marks. There were many students who mentioned the information in M1 (asymmetric stretching and bonds vibrate) or M2 (polarity and dipole changes) more than one time but could only receive one mark. Teachers need to remind students each mark is a different topic or concept.
Outline one approach to controlling industrial emissions of carbon dioxide.
[1]
Any one of:
capture where produced «and stored» [✔]
use scrubbers to remove [✔]
use as feedstock for synthesizing other chemicals [✔]
carbon credit/tax/economic incentive/fines/country specific action [✔]
use alternative energy
OR
stop/reduce use of fossil fuels for producing energy [✔]
use carbon reduced fuels «such as methane» [✔]
increase efficiency/reduce energy use [✔]
This question was reasonably answered although there were many students who gave vague answers that did not receive marks. Carbon cannot be “filtered out” and the process of “carbon capture or scrubbing” is different from filtering.