a level chemistry reaction preference question
so the mark scheme says:
(b) (i) Advantage; reaction goes to completion, not reversible
or faster - 1
Disadvantage; reaction vigorous/dangerous
(exothermic must be qualified)
or HCl(g) evolved/toxic
or CH3COCl expensive
but i dont get how the reaction being reversible is an advantage? i'll link the question below
(b) (i) Advantage; reaction goes to completion, not reversible
or faster - 1
Disadvantage; reaction vigorous/dangerous
(exothermic must be qualified)
or HCl(g) evolved/toxic
or CH3COCl expensive
but i dont get how the reaction being reversible is an advantage? i'll link the question below
(edited 1 year ago)
It seems like the mark scheme is talking about reaction 2 being irreversible. This would mean that all the reactants would be used up to form as much product possible. In a reversible reaction like reaction 1 however, some of the reactants will not get used up as there will be equal rates of the forward and backward reactions occurring at equilibrium. So it's easier to get a higher yield with the irreversible reaction 2 as that goes to completion than the reversible reaction 1 as that is reversible and would instead just form an equilibrium.
That's what I think anyway. I hope that makes sense.
That's what I think anyway. I hope that makes sense.
Original post by kaorimiyazono
It seems like the mark scheme is talking about reaction 2 being irreversible. This would mean that all the reactants would be used up to form as much product possible. In a reversible reaction like reaction 1 however, some of the reactants will not get used up as there will be equal rates of the forward and backward reactions occurring at equilibrium. So it's easier to get a higher yield with the irreversible reaction 2 as that goes to completion than the reversible reaction 1 as that is reversible and would instead just form an equilibrium.
That's what I think anyway. I hope that makes sense.
That's what I think anyway. I hope that makes sense.
yea thats what i was thinking as well. so i put it down as a disadvantage but the mark scheme says its an advantage???
Well it depends what way round you view it:
Reaction 1 is reversible so establishes equilibrium = disadvantage.
Reaction 2 is irreversible and therefore goes to completion = advantage.
From the second point of the mark scheme I think it's talking about it from the 2nd perspective because reaction 2 is the dangerous one, not reaction 1.
(Which actually doesn't fit the way the question is worded. Mmm idk why the mark scheme is phrased like that, but if you're really clear in your answer about what things you say are an advantage and what things are a disadvantage I'd hope you'd still get the marks.)
Reaction 1 is reversible so establishes equilibrium = disadvantage.
Reaction 2 is irreversible and therefore goes to completion = advantage.
From the second point of the mark scheme I think it's talking about it from the 2nd perspective because reaction 2 is the dangerous one, not reaction 1.
(Which actually doesn't fit the way the question is worded. Mmm idk why the mark scheme is phrased like that, but if you're really clear in your answer about what things you say are an advantage and what things are a disadvantage I'd hope you'd still get the marks.)
(edited 1 year ago)
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