. Calculate the heat for the overall reaction: Mg(s) + 1/2O2 → MgO(s) given the heats of reaction below: Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) ∆H = –143 kJ MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(g) ∆H = –216 kJ H2(g) + 1/2O2 → H2O(l) ∆H = –285 kJ (A) –644 kJ (B) –212 kJ (C) +644 kJ (D) –74 kJ (E) +74 kJ Share with your friends Share 0 Vartika Jain answered this Dear Student, (i) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) ∆Hi=-143 kJ(ii) MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(g) ∆Hii=-216 kJ(iii) H2(g) + 12O2(g) → H2O(l) ∆Hiii=-285 kJThe required equation is,(iv)Mg(s) + 12O2(g) → MgO(s) ∆H?The above equation can be obtained as, (iv)=[(i)-(ii)]+(iii)∆H=[∆Hi-∆Hii]+∆Hiii =[-143-(-216)]+(-285) =73-285 =-212 kJHence, correct answer is (B) 0 View Full Answer