DP Chemistry (first assessment 2025)
Question 22M.1A.SL.TZ1.26
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.SL.TZ1.26 |
| Level | SL | Paper | 1A | Time zone | TZ1 |
| Command term | Apply | Question number | 26 | Adapted from | N/A |
26.
[Maximum mark: 1]
22M.1A.SL.TZ1.26
Which statement explains the Lewis acid–base nature of the chloride ion in this reaction?
C2H5+ + Cl– → C2H5Cl
A. Lewis base because it donates a pair of electrons
B. Lewis base because it accepts a pair of electrons
C. Lewis acid because it donates a pair of electrons
D. Lewis acid because it accepts a pair of electrons
[1]
Markscheme
A
Examiners report
A discriminating question in which high scoring candidates had much greater success in explaining the Lewis acid-base nature of the chloride ion in the given reaction. The next two common incorrect answers were B and D showing a lack of understanding of the Lewis acid-base concept.
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.6—Strong and weak acids and bases differ in the extent of ionization. Recognize that acid–base equilibria lie in the direction of the weaker conjugate. and are strong acids, and group 1 hydroxides are strong bases.