Give an example of a reaction for each of the following relations between `DeltaH and DeltaU`: (i) `DeltaU lt DeltaH`
(ii) `DeltaU gt DeltaH`
(iii) `DeltaU=DeltaH`.

Explanation

In a reaction, if gaseous substance (either as a reactant or as a product or both) participates, the change in enthalpy in the reaction at constant pressure and temperature is given by `DeltaH=DeltaU+DeltanRT`. If `Deltan` (total number of moles of gaseous products-total number of moles of gaseous reactants)`gt0,lt0 or=0`, then `DeltaH gt DeltaU, DeltaH lt Delta U` orr `DeltaH=DeltaU` respectively.
(i) `2H_(2)O(g)to2H_(2)(g)+O_(2)(g),Deltan=(2+1)-2=+1.` so, `DeltaH gt DeltaU`
(ii) `2H_(2)(g)+O_(2)(g)to2H_(2)O(l),Deltan=0-(2+1)=-3.` so, `Delta H lt DeltaU`
(iii) `N_(2)(g)+O_(2)(g) to 2NO(g),Deltan=2-(1+1)=0`. so, `DeltaH=DeltaU`.