DP Chemistry (first assessment 2025)
Question 22M.1A.SL.TZ2.19
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.SL.TZ2.19 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | Solve | Question number | 19 | Adapted from | N/A |
19.
[Maximum mark: 1]
22M.1A.SL.TZ2.19
Which of the 0.001 mol dm−3 solutions is most likely to have a pH of 11.3?
A. Ca(OH)2 (aq)
B. H3PO4 (aq)
C. NaOH (aq)
D. NH4OH (aq)
[1]
Markscheme
A
Examiners report
This required calculation of pH of a base – not an easy task for SL candidates without a calculator. 28% of the candidates answered the question correctly.
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.