Challenge your learners to apply their knowledge of physical and inorganic chemistry to less familiar contexts, such as haemoglobin 

This resource accompanies the Education in Chemistry article Carbon monoxide – the silent killer.

Learning objectives

  1. Review bonding concepts and use them to describe the bonding in haemoglobin (task 1).
  2. Apply the equilibrium law and Le Chatelier’s principle to the equilibrium reactions occurring between haemoglobin, oxygen and carbon monoxide (task 2).
  3. Draw conclusions from half-cell equations and their E0 values about the relative stabilities of binding ligands in complex ions (task 3).
  4. Analyse the half-cell equations and their E0 values to examine the effect of pH on redox potential and the final oxidation state of the reductant (task 4).
  • Screenshots of the chemistry of iron teacher notes and student sheets and a carbon monoxide molecule

    Download this

    Worksheet, for age range 16–18

    Practice questions for learners to apply their understanding of bonding, redox and equilibrium in transition metal chemistry to less familiar contexts.

    Download the student worksheet as MS Word and pdf and the teacher notes and answers as MS Word or pdf.

How to use

There are four tasks in the resource, which can be used in several ways to fit in with the scheme of learning and assessment plan for the programme. For example:

  • as part of the teaching programme for transition metals (tasks 1 and 2) and redox chemistry (tasks 3 and 4)
  • as a whole class activity, eg a time framed, team-based learning challenge
  • as part of a revision programme reviewing topics of bonding, chemical equilibrium, transition metal and redox chemistry
  • as a summative homework assessment at the end of teaching transition metals
  • as part of a synoptic summative assessment of physical and inorganic chemistry

Hints are provided for some questions to make them more accessible to a wider range of learners.

The second part of task 4 is intended to be a challenge. Learners will construct full ionic equations from half-cell equations and their respective Evalues for rusting in alkaline conditions.

Cross-curricular links

A diagram of the carboxyhaemoglobin complex, with a coordinate bond from the carbon lone pair on the carbon monoxide molecule to the central Fe2+ ion in the haem group. There is a triple bond between C and O in the carbon monoxide ligand. There is also a

Source: © Royal Society of Chemistry

Carbon monoxide is a stronger ligand than oxygen and leads to carboxyhaemoglobin forming instead of oxyhaemoglobin

Highlight the overlapping topics with biology and environmental chemistry when teaching incomplete combustion of hydrocarbons to your 16–18 learners. Use the context of haemoglobin to reinforce applications of transition metal chemistry – in particular, complex ions and the concepts of chemical equilibrium occurring in ligand exchange. Why not discuss the role of research and development in finding solutions to complex long-term health issues, such as carbon monoxide poisoning? Learners could also investigate this topic as an individual research project in qualifications such as the Extended Project Qualification (EPQ) and Advanced Skills Challenge Certificate.

More resources

  • Revise key definitions and concepts using the Transition metal chemistry starter for 10 with your 16–18 learners. 
  • Include UN Sustainable development goal 3, which focuses on good health and well-being, when teaching transition metals with this knowledge retrieval, exam-style questions, comprehension task and quiz on cisplatin and other anticancer drugs.
  • Meet John, a medicinal chemist, who is making the difference by developing new medicines for infectious diseases such as malaria and tuberculosis.
  • Use this lesson plan to improve learners’ understanding of key topics, such as complex ions’ bonding and shapes, ligand exchange and stability constants, by asking them to explain the topics to each other.