Question

H2 + Ci2---> 2HcI H-H/104kj ; CI-CI/78kj ; H-CI/106kj

Answer 1

∆H=∆H(H)-(∆H(Cl)+∆H(HCl)
-78=104-(∆H{HCl}-104)
∆H{HCl}=-104+106+78
=-80kcl/mol