DP Chemistry (first assessment 2025)
Question 19M.1A.HL.TZ2.8
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.HL.TZ2.8 |
| Level | HL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 8 | Adapted from | N/A |
8.
[Maximum mark: 1]
19M.1A.HL.TZ2.8
What is the oxidation state of the metal ion and charge of the complex ion in [Co(NH3)4Cl2]Cl?
[1]
Markscheme
C
Examiners report
This was one of the most challenging questions on the paper and it discriminated well between high scoring and low scoring candidates. 57 % of the candidates were able to use the formula of the compound to deduce the oxidation state of the metal ion and the charge of the complex ion. The most commonly chosen distractor was B where the charge of the complex ion was correct but the charge of the metal ion was not. Some teachers commented that the question was challenging but reasonable.
Syllabus sections
Structure 3. Classification of matter » Structure 3.1—The periodic table: Classification of elements » Structure 3.1.6—The oxidation state is a number assigned to an atom to show the number of electrons transferred in forming a bond. It is the charge that atom would have if the compound were composed of ions. Deduce the oxidation states of an atom in an ion or a compound.