DP Chemistry (first assessment 2025)
Question 22N.1A.SL.TZ0.25
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.SL.TZ0.25 |
| Level | SL | Paper | 1A | Time zone | TZ0 |
| Command term | Apply | Question number | 25 | Adapted from | N/A |
25.
[Maximum mark: 1]
22N.1A.SL.TZ0.25
Which homologous series has the general formula CnH2nO (n > 2)?
A. Alcohols
B. Carboxylic acids
C. Ethers
D. Ketones
[1]
Markscheme
D
Examiners report
49% of the candidates deduced that ketones had the general formula CnH2nO. The distractors were chosen with almost equal frequency. The question had good discrimination between high-scoring and low-scoring candidates.
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.6—Strong and weak acids and bases differ in the extent of ionization. Recognize that acid–base equilibria lie in the direction of the weaker conjugate. and are strong acids, and group 1 hydroxides are strong bases.
Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.3—A homologous series is a family of compounds in which successive members differ by a common structural unit, typically CH2. Each homologous series can be described by a general formula. Identify the following homologous series: alkanes, alkenes, alkynes, halogenoalkanes, alcohols, aldehydes, ketones, carboxylic acids, ethers, amines, amides and esters.