DP Chemistry (first assessment 2025)
Question 21M.2.SL.TZ1.5
| Date | May 2021 | Marks available | [Maximum mark: 5] | Reference code | 21M.2.SL.TZ1.5 |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Deduce, Justify, State, Suggest | Question number | 5 | Adapted from | N/A |
5.
[Maximum mark: 5]
21M.2.SL.TZ1.5
Ethanol is obtained by the hydration of ethene, C2H4.
(a(i))
State the class of compound to which ethene belongs.
[1]
Markscheme
alkene ✔
(a(ii))
State the molecular formula of the next member of the homologous series to which ethene belongs.
[1]
Markscheme
C3H6 ✔
Accept structural formula.
(b)
Justify why ethene has only a single signal in its 1H NMR spectrum.
[1]
Markscheme
hydrogen atoms/protons in same chemical environment ✔
Accept “all H atoms/protons are equivalent”.
Accept “symmetrical”
(c)
Suggest two possible products of the incomplete combustion of ethene that would not be formed by complete combustion.
[1]
Markscheme
carbon monoxide/CO AND carbon/C/soot ✔
(d)
A white solid was formed when ethene was subjected to high pressure.
Deduce the type of reaction that occurred.
[1]
Markscheme
«addition» polymerization ✔
Syllabus sections
Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.2—Functional groups give characteristic physical and chemical properties to a compound. Organic compounds are divided into classes according to the functional groups present in their molecules. Identify the following functional groups by name and structure: halogeno, hydroxyl, carbonyl, carboxyl, alkoxy, amino, amido, ester, phenyl.
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.
Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.10—Proton nuclear magnetic resonance spectroscopy (1H NMR) gives information on the different chemical environments of hydrogen atoms in a molecule. Interpret 1H NMR spectra to deduce the structures of organic molecules from the number of signals, the chemical shifts, and the relative areas under signals (integration traces).
Reactivity 1. What drives chemical reactions? » Reactivity 1.3—Energy from fuels » Reactivity 1.3.2—Incomplete combustion of organic compounds, especially hydrocarbons, leads to the production of carbon monoxide and carbon. Deduce equations for the incomplete combustion of hydrocarbons and alcohols.
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.