Hi everyone!
I'm having some trouble getting my head around Le Chatelier's principle, specifically how changes to the system favours certain reactions. I was given a question today:
Equation 1: Hb(aq) + 4O2(aq) ⇌ Hb(O2)4(aq)
Equation 2: Hb(aq) + 4CO(aq) ⇌ Hb(CO)4
Patients suffering from carbon monoxide poisoning are treated with pure oxygen (hyperbaric) to remove CO from the Hb. With reference to Le Chatelier's theory, explain how this treatment works.
I wrote this:
Pure oxygen will be added to the system. Le Chatelier's theory states that the system will attempt to favour a reaction in order to counteract a change to the system. Therefore, to counteract an increase of pure oxygen, the system will favour the reverse reaction in order to use up the CO bound to the Hb.
But this doesn't really make sense... I know that you will have to favour the reverse reaction in order to remove the CO, but if the oxygen was added to the reactants side then you'd have to favour the forward reaction to remove it but then you'd just make more CO! If someone could explain this I would be really grateful.
Thanks!
Hey vehura, you might find this
thread on carbon monoxide poisoning helpful.
I feel like the combined equation makes it a lot easier to understand what's happening. You are adding more on the right side, so in order to counteract the change, the equilibrium shifts towards the left, the side with more O2 bonded to the haemoglobin.
Hb(O2)4(aq)+4CO(aq)⇌Hb(CO)4(aq)+4O2(aq)
I think instead of thinking about it as 'using up' the HbCO, it would be better to think about it like how the Hb much rather prefers bonding to CO (so there is a much larger amount of HbCO than HbO) but when you flood the system with oxygen, some of the Hb bonds with bonds oxygen instead of carbon monoxide. The increased amount of reactants on the left makes the reverse reaction become favoured.
My chem teacher used an analogy iirc with Haemoglobin being a person who has a much higher chance of picking toxic people that don't treat it well (CO) to hang with, despite there being nice, caring people (O2). We if we flood their life with the nice O2 people then it kind of increases the likelihood that they will hang with more nice people than toxic people.
I hope this isn't too confusing i'm not sure if i've phrased it clear enough, it's difficult to get straight away, i recommend that thread though it has some really good explanations!
I personally think your answer would be fine, but maybe remove the 'in order to use up the CO part'? Also maybe specify that you mean equation2 when you are talking about it favouring the reverse reaction.
edit: Bri beat me hehe, i'll leave in case it helps having it explained different ways