DP Chemistry (first assessment 2025)
Question 21M.1A.SL.TZ2.27
Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.1A.SL.TZ2.27 |
Level | SL | Paper | 1A | Time zone | TZ2 |
Command term | State | Question number | 27 | Adapted from | N/A |
27.
[Maximum mark: 1]
21M.1A.SL.TZ2.27
Which is a propagation step in the free-radical substitution mechanism of ethane with chlorine?
A. C2 → 2 •C
B. •C2H5 + C2 → C2H5C + •C
C. •C2H5 + •C → C2H5C
D. C2H6 + •C → C2H5C + •H
[1]
Markscheme
B
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.3—Electron sharing reactions » Reactivity 3.3.3—Radicals take part in substitution reactions with alkanes, producing a mixture of products. Explain, using equations, the propagation and termination steps in the reactions between alkanes and halogens.