DP Chemistry (first assessment 2025)
Question 19M.2.HL.TZ1.25a
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.HL.TZ1.25a |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Identify | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 1]
19M.2.HL.TZ1.25a
(a)
Identify the chiral carbon atom using an asterisk, *.
[1]
Markscheme
[✔]
Examiners report
Some candidates had difficulty identifying the chiral carbon in a methadone structure, with quite a few varied answers. However, many managed to mark the correct carbon.
Syllabus sections
Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.7—Stereoisomers have the same constitution (atom identities, connectivities and bond multiplicities) but different spatial arrangements of atoms. Describe and explain the features that give rise to cis-trans isomerism; recognize it in non-cyclic alkenes and C3 and C4 cycloalkanes. Draw stereochemical formulas showing the tetrahedral arrangement around a chiral carbon. Describe and explain a chiral carbon atom giving rise to stereoisomers with different optical properties. Recognize a pair of enantiomers as non-superimposable mirror images from 3D modelling (real or virtual).