DP Chemistry (first assessment 2025)
Question 22N.1A.SL.TZ0.22
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.SL.TZ0.22 |
| Level | SL | Paper | 1A | Time zone | TZ0 |
| Command term | Apply | Question number | 22 | Adapted from | N/A |
22.
[Maximum mark: 1]
22N.1A.SL.TZ0.22
Which substance is the reducing agent in the given reaction?
H+ (aq) + 2H2O (l) + 2MnO4− (aq) + 5SO2 (g) → 2Mn2+ (aq) + 5HSO4− (aq)
A. H+
B. H2O
C. MnO4−
D. SO2
[1]
Markscheme
D
Examiners report
50% of the candidates identified SO2 as the reducing agent. The most commonly chosen distractor was MnO4−. The question had good discrimination between high-scoring and low-scoring candidates.
Syllabus sections
Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.2—Electron transfer reactions » Reactivity 3.2.1—Oxidation and reduction can be described in terms of electron transfer, change in oxidation state, oxygen gain/loss or hydrogen loss/gain. Deduce oxidation states of an atom in a compound or an ion. Identify the oxidized and reduced species and the oxidizing and reducing agents in a chemical reaction.
Reactivity 2. How much, how fast and how far? » Reactivity 2.3—How far? The extent of chemical change » Reactivity 2.3.6—The equilibrium law is the basis for quantifying the composition of an equilibrium mixture. Solve problems involving values of K and initial and equilibrium concentrations of the components of an equilibrium mixture.
Reactivity 2. How much, how fast and how far? » Reactivity 2.2—How fast? The rate of chemical change » Reactivity 2.2.12—The Arrhenius equation uses the temperature dependence of the rate constant to determine the activation energy. Describe the qualitative relationship between temperature and the rate constant. Analyse graphical representations of the Arrhenius equation, including its linear form.