DP Chemistry (first assessment 2025)
Question 22N.2.SL.TZ0.b
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.2.SL.TZ0.b |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
22N.2.SL.TZ0.b
Compound A can also react with bromine. Describe the change observed if A is reacted with bromine.
[1]
Markscheme
brown/orange/red/yellow to colourless ✔
Do not accept clear for colourless.
Examiners report
Although it was a straightforward organic question, 22% of the candidates left it blank, indicating less confidence in answering the organic chemistry questions. 40% of the candidates gained the mark for the decolourization of bromine. One of the common mistakes was reversing the colour change and another was using the term "clear" instead of "colourless".
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.4—Electron-pair sharing reactions » Reactivity 3.4.5—Alkenes are susceptible to electrophilic attack because of the high electron density of the carbon–carbon double bond. These reactions lead to electrophilic addition. Deduce equations for the reactions of alkenes with water, halogens, and hydrogen halides.