DP Chemistry (first assessment 2025)
Question 22M.2.HL.TZ2.d(v)
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.HL.TZ2.d(v) |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Justify, Predict | Question number | d(v) | Adapted from | N/A |
d(v).
[Maximum mark: 2]
22M.2.HL.TZ2.d(v)
Predict, giving a reason, the major product of reaction between but-1-ene and steam.
[2]
Markscheme
CH3CH2CH(OH)CH3 ✔
«secondary» carbocation/CH3CH2CH+CH3 more stable ✔
Do not accept “Markovnikov’s rule” without reference to carbocation stability.
Examiners report
Product was correctly predicted by many, but most used Markovnikov's Rule to justify this, failing to mention the stability of the secondary carbocation, i.e., the chemistry behind the rule.
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.4—Electron-pair sharing reactions » Reactivity 3.4.11—Alkenes readily undergo electrophilic addition reactions. Describe and explain the mechanisms of the reactions between symmetrical alkenes and halogens, water and hydrogen halides.