1.

Give an example of a physical change for each of the following relations between DeltaH and DeltaU: (i) DeltaH gt DeltaU (ii) DeltaH lt DeltaU (iii) DeltaH~~DeltaU.

Answer»

Solution :The EQUATION `DELTAH=DELTAU+DeltanRT` can be used in case of a process involving PHASE change of a substance.
(i) `H_(2)O(l)toH_(2)O(g)`. Here, `Deltan=+1`. So, `DeltaH gt DeltaU`.
(ii) `H_(2)O(g)toH_(2)O(l)`. Here `Deltan=-1`. So, `DeltaH lt DeltaU`.


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