Assume each reaction is carried out in an open container.
For which reaction will `DeltaH=DeltaU` ?

Options

A. `H_(2)(g) + Br_(2)(g) to 2HBr(g)`
B. `C(s) + 2H_(2)O(g) to 2H_(2)(g) +CO_(2)(g)`
C. `PCl_(5)(g) to PCl_(3) + Cl_(2)(g)`
D. `2CO(g) + O_(2)(g) to 2CO_(2)(g)`

Answer

A

Explanation

As we know that, `DeltaH=DeltaE+pDeltaV " or " DeltaH= DeltaE+ Deltan_(g) RT`
where , `Deltan_(g) to ` number of gaseous moles of product -number of gaseous moles of reactant
If `Deltang=0` (for reactants in which the total number of moles of gaesous reactants ), therefore `DeltaH-DeltaE` So, for reaction (a) `Deltan=2-2=0`
Hence, for reaction (a) `DeltaH=DeltaE`