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Suggest and explain an indirect method to calculate lattice enthalpy of magnesium bromide. |
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Answer» Solution :Born Haber.s cycle method: `Mg(s)+Br_(2)(l) to MgBr_(2)(s) "" DeltaH_f^0` Sublimation : `Mg_((s)) to Mg_((g)) "" DeltaH_1^0` Ionisation : `Mg_((g)) to Mg_((g))^(2+) + 2e^(-) "" DeltaH_2^0` Vapourisation : `Br_(2(l)) to Br_(2(g)) "" DeltaH_3^0` Dissociation : `Br_(2(g)) to 2Br_((g)) "" DeltaH_4^0` Electron affinity : `2Br_((g)) + 2e^(-) to 2Br_((g))^(-) "" DeltaH_5^0` LATTICE ENTHALPY : `Mg_((g))^(2+) + 2Br_((g))^(-) to MgBr_((2)s) "" DeltaH_6^0` =? `DeltaH_f^0 = DeltaH_1^0+DeltaH_2^0 + DeltaH_3^0+ DeltaH_4^0 + DeltaH_5^0 + DeltaH_6^0` `DeltaH_6^0=DeltaH_f^0 -(DeltaH_1^0+DeltaH_2^0+DeltaH_3^0+DeltaH_4^0+DeltaH_5^0)` If we KNOW the VALUES of `DeltaH_f^0,DeltaH_1^1,DeltaH_2^0, DeltaH_3^0, DeltaH_4^0` and `DeltaH_5^0` . We can calculate the value of `DeltaH_6^0` by indirect method. |
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