IE1 and IE2 of Mg are 178 and 348 kcal mol-1. The energy required for the reaction Mg→Mg2++2e- is __________.

(i) Mg(g)⟶Mg⊕(g)+e−, IE1=178 kcal mol−1 (ii) Mg⊕(g) ⟶Mg2+(g)+e−, IE2=348kcalmol−1Adding (i) and (ii), we have---------- Mg(g)⟶Mg2+(g)+2e− ----------∴ E = IE1 + IE2 = 178 +348 =526 kcal