DP Chemistry (first assessment 2025)
Question 19M.2.HL.TZ1.7a
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.7a |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Draw | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 2]
19M.2.HL.TZ1.7a
(a)
Draw the structure of the repeating unit of starch and state the type of linkage formed between these units.
Type of linkage:
[2]
Markscheme
continuation bonds AND -O- attached to just one end AND both H-atoms on end carbons must be on the same side [✔]
Note: Square brackets not required.
Ignore “n” if given.
Mark may be awarded if a polymer is shown but with the repeating unit clearly identified.
Type of linkage:
glycosidic [✔]
Note: Accept “ether”.
Examiners report
Hardly any students were able to draw the required repeating unit, but in contrast almost all knew that the monomers were joined by a glycosidic linkage.
Syllabus sections
Structure 2. Models of bonding and structure » Structure 2.4—From models to materials » Structure 2.4.6—Condensation polymers form by the reaction between functional groups in each monomer with the release of a small molecule. Represent the repeating unit of polyamides and polyesters from given monomer structures.