O Level Chemistry Questions
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My old thread got locked due to inactivity.. Maybe the moderators can merge this post into the old thread (last post on 2/10/10) to reduce repetition..
A quick question - what is the detriment of using iron (II) chloride + carbonic acid to form iron (II) carbonate? Is it because carbonic acid is a weak acid?
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Originally posted by gohby:
My old thread got locked due to inactivity.. Maybe the moderators can merge this post into the old thread (last post on 2/10/10) to reduce repetition..
A quick question - what is the detriment of using iron (II) chloride + carbonic acid to form iron (II) carbonate? Is it because carbonic acid is a weak acid?
Hello again Gohby.The method is unsuitable because the H+(aq) (from H2CO3, or HCl if you use the equation FeCl2 + H2CO3 ---> FeCO3 + 2HCl) will immediately react with any FeCO3(s) formed, to get back your original reactants FeCl2(aq) and H2CO3, which decomposes into CO2 and H2O.
Yes, in a way it is indeed because carbonic acid is a weak acid, but your 'O' level student is unlikely to understand exactly how this is related to why the method is unsuitable. Because the acid is relatively weak, the conjugate base is relatively strong, and consequently the carbonate ion base is readily protonated to form carbonic acid, which exists in equilibrium with, and hence decomposes into, carbon dioxide and water.
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Oh ok! Got it.. Thanks!
