F.4 Displacement reaction

no way.
practically, no metal oxide can "dissolve" in water.
oxide ion is too unstable in water; it reacts with water to give hydroixde ions:
O(2-) + H2O ------> 2OH(-)

therefore, group(I)'s oxides and some of group(II)'s oxides, like sodium oxide, potassium oxide and calcium oxide, do NOT "dissolve in water.
instead, they REACT, react with water to give hydroxides ---- their identities are no longer "dissolved metal oxides"

on the other hand, those metal oxides unreactive to water are insoluble, like copper(II) oxide, iron(III) oxide, aluminium oxide.
charge density of oxide ion is high. lattice enthalpy of its compounds is large, making dissolution endothermic and unfeasible.


well, displacement does not necessary to occur in aqueous medium.
thermite, mixture of iron(III) oxide and aluminium, burns vigorously (not needing oxygen) to form molten iron. it's used in welding rails in railways.


2011-02-09 14:53:49 補充：
Knowledge:
Metal oxide, please.

2011-02-09 15:50:33 補充：
i wonder whether carbon reduction is also a "displacement".

displacement also occurs in organic chemistry, say, methane + bromine; ethanol + thionyl chloride; iodomethane + ammonia...

There is also halogen displacement reaction:
Reactivity of Gp VII halogen: F>Cl>Br>I
The more reactive halogen will displace the less reactive halogen ion to form more reactive halogen ion and less reactive halogen.

For example: Cl2 + 2Br- ---> 2Cl- + Br2

2011-02-09 15:21:40 補充：
Yes, i know you guys are talking about metal oxide.
just wanna give some extra info about the displacement reaction.