Question

The standard enthalpy of formation of `H_(2)(g)` and `Cl_(2)(g)` and `HCl(g)` are `218 kJ//mol`, `121.88 kJ//mol` and `-93.31 kJ//mol` respectively. Calculate standard enthalpy change in `kJ` for
`(1)/(2)H_(2)(g)+(1)/(2)Cl_(2)(g)toHCl(g)`
A. `+431.99
B. `-262.14`
C. `-431.99`
D. `+247.37`

Answer 1

Correct Answer - B
`Delta_(r )H=DeltaH_("products")-DeltaH_("reactants")`
`=-92.3-[(218)/(2)+(121.68)/(2)]`
`=-92.3-[109+60.84]`
`=-262.14 kJ//mol`