The standard enthalpy of formation of hypothetical MgCl is -125kJ mol^(-1) and for MgCl_(2) is -642 kJ mol^(-1). What is the enthalpy of the disproportionation of MgCl ?

The standard enthalpy of formation of hypothetical MgCl is -125kJ mol^

1.	The standard enthalpy of formation of hypothetical MgCl is -125kJ mol^(-1) and for MgCl_(2) is -642 kJ mol^(-1). What is the enthalpy of the disproportionation of MgCl ?
Answer» `-492 KJ mol^(-1)` `-392 kJ mol^(-1)` `-767kJ mol^(-1)` `-517 kJ mol^(-1)` Solution :(i) `Mg_((s)) + Cl_(2(g)) RARR MgCl_(2(s)) , Detlta H_(1) = - 642` (ii) `Mg_((s)) + 1//2Cl_(2(g)) rarr MgCl_((s)) , DELTA H_(2) = - 125` (iii) `2MgCl rarr MgCl_(2) + Mg, Delta H`= ? `Delta H = Delta H_(1)- Delta H_(2) = - 392 kJ mol^(-1)`