DP Chemistry (first assessment 2025)
Question 22N.1A.HL.TZ0.22
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.HL.TZ0.22 |
| Level | HL | Paper | 1A | Time zone | TZ0 |
| Command term | Solve | Question number | 22 | Adapted from | N/A |
22.
[Maximum mark: 1]
22N.1A.HL.TZ0.22
For the reaction 2 (g) + 3Cl2 (g) 2Cl3 (g) at a certain temperature, the equilibrium concentrations are (in mol dm−3):
[2] = 0.20, [Cl2] = 0.20, [Cl3] = 2.0
What is the value of Kc?
A. 0.25
B. 50
C. 2500
D. 5000
[1]
Markscheme
C
Examiners report
Over 72% of the candidates were able to calculate value of Kc from the concentrations given, with the other distractors being about equally favoured. Some teachers expressed concern at candidates having to do this without a calculator, but the figures were quite easy to manipulate and the number answering correctly indicates it did not hinder many candidates.
Syllabus sections
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.