Date | November 2018 | Marks available | 2 | Reference code | 18N.3.hl.TZ0.23 |
Level | HL | Paper | 3 | Time zone | TZ0 |
Command term | Outline | Question number | 23 | Adapted from | N/A |
Question
Scientists have developed various analytical techniques.
State an analytical technique used to separate anabolic steroids from other compounds in an athlete’s urine or blood.
Ethanol in breath can be detected by a redox reaction. Outline this method of detection. An equation is not required.
Markscheme
gas chromatography/GC
OR
high performance liquid chromatography/HPLC ✔
Accept “chromatography”, “TLC/thin-layer chromatography”, “paper chromatography” OR “extraction”.
Do not accept just “mass spectrometry/MS” but do not penalize any reference to MS with HPLC or GC (eg GC-MS).
ALTERNATIVE 1:
Any two of:
«blow through tube of» acidified «orange» potassium dichromate(VI)/K2Cr2O7/dichromate/Cr2O72– ✔
Cr(VI)/Cr6+/Cr2O72– reduced to Cr(III)/Cr3+✔
colour changes «from orange» to green
OR
colour change is monitored ✔
ALTERNATIVE 2:
oxygen reduced to water
OR
ethanol oxidized to ethanoic/acetic acid ✔
current measured ✔
Accept “ethanol oxidized to ethanal/acetaldehyde”.