DP Chemistry (first assessment 2025)
Question 22M.1A.SL.TZ2.24
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.SL.TZ2.24 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | State | Question number | 24 | Adapted from | N/A |
24.
[Maximum mark: 1]
22M.1A.SL.TZ2.24
How many dichlorinated butane isomers can be formed by the halogenation of CH3CH2CH2CH3 with excess Cl2 in the presence of UV light?
A. 4
B. 6
C. 8
D. 10
[1]
Markscheme
B
Examiners report
Candidates had to work out the possible number of isomers of dichlorobutane and the majority only thought of 4 of the 6 possible isomers. 32% of the candidates obtained the correct answer.
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.