DP Chemistry (first assessment 2025)
Question 22M.2.SL.TZ2.d(ii)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.SL.TZ2.d(ii) |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Deduce | Question number | d(ii) | Adapted from | N/A |
d(ii).
[Maximum mark: 1]
22M.2.SL.TZ2.d(ii)
Write the equation for the reaction between but-2-ene and hydrogen bromide.
[1]
Markscheme
CH3CH=CHCH3 + HBr (g) → CH3CH2CHBrCH3
Correct reactants ✔
Correct products ✔
Accept molecular formulas for both reactants and product
Examiners report
Well done in general and most candidates wrote correct reagents, eventually losing a mark when considering H2 to be a product alongside 2-bromobutane.
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.