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A-Level Reversible reactions and the position of equilibrium: worked solution
2 marks. Full working, one step per line.
Question
Explain why giving a patient pure oxygen to breathe is an effective treatment for carbon monoxide poisoning.
Worked answer
CO binds to haemoglobin in a reversible equilibrium, e.g. HbO2 + CO = HbCO + O2, and CO binds strongly, tying up haemoglobin as carboxyhaemoglobin. Breathing pure oxygen greatly raises the concentration/partial pressure of O2. By Le Chatelier's principle the equilibrium shifts to the left (to oppose the added O2), displacing CO from the haemoglobin and regenerating oxyhaemoglobin HbO2. This releases the bound CO (which is then exhaled) and restores oxygen transport.
Practise this topic
This question is part of A-Level Reversible reactions and the position of equilibrium, in A-Level H2 Chemistry.