DP Chemistry (first assessment 2025)
Question 21M.2.HL.TZ2.6
| Date | May 2021 | Marks available | [Maximum mark: 4] | Reference code | 21M.2.HL.TZ2.6 |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Determine | Question number | 6 | Adapted from | N/A |
6.
[Maximum mark: 4]
21M.2.HL.TZ2.6
Bromate and bromide ions react in acidic aqueous solution.
BrO3− (aq) + 5Br− (aq) + 6H+ (aq) → 3Br2 (l) + 3H2O (l)
The following rate data was collected.
(a)
Determine the rate expression for the reaction.
[2]
Markscheme
BrO3–: 1/first AND Br–: 1/first AND H+: 2/second ✓
«Rate =» k[BrO3−][Br−][H+]2 ✓
M2: Square brackets required for the mark.
(b)
Determine the value and unit of the rate constant using the rate expression in (a).
[2]
Markscheme
«k ==» 8.0 ✓
mol−3 dm9 s−1 ✓
Syllabus sections
Reactivity 2. How much, how fast and how far? » Reactivity 2.2—How fast? The rate of chemical change » Reactivity 2.2.11—The rate constant, k, is temperature dependent and its units are determined from the overall order of the reaction. Solve problems involving the rate equation, including the units of k.