question_answer

An ionic compound \[A{{X}_{3}}\,\,(s)\] is formed between a metal A and a non-metal X (outermost shell configuration of \[X\,\,=\,\,n{{s}^{2}}n{{p}^{5}}\]). Find the enthalpy of formation (magnitude) of \[A{{X}_{3}}\,\,(s)\] with the help of the following data. (Non-metal X is found to exist in nature as a diatomic gas)

\[\Delta {{H}_{sublimation}}\,\,A\left( s \right)\,\,=\,\,100\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{I.E{{.}_{1}}}}A\left( g \right)\,\,=\,\,60\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{I.E{{.}_{2}}}}A\left( g \right)\,\,=\,\,150\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{I.E{{.}_{3}}}}A\left( g \right)\,\,=\,\,280\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{diss}}\,\,{{X}_{2}}\left( g \right)\,\,=\,\,80\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{e.g}}\,\,X\left( g \right)\,\,=\,\,-\,110\,\,Kcal\,/\,mol\]

\[\Delta {{H}_{Lattice\text{ }energy}}\,\,A\,\,{{X}_{3}}\,\left( s \right)\,\,=\,\,-\,470\,\,Kcal\,/\,mol\]

Answer:

-90.00