Heat of formation of 2 moles of NH_(3)(g) " is" -90 kJl bond energies of H-H and N-H bonds are 435 kJ and 390 kJ mol^(-1) respectively. The value of the bond energy of N -= N is (1000- (x^(2) + x +25)) kJ/mol What is x ?

Heat of formation of 2 moles of NH_(3)(g) " is" -90 kJl bond energies

1.	Heat of formation of 2 moles of NH_(3)(g) " is" -90 kJl bond energies of H-H and N-H bonds are 435 kJ and 390 kJ mol^(-1) respectively. The value of the bond energy of N -= N is (1000- (x^(2) + x +25)) kJ/mol What is x ?
Answer» Solution :From the data we can say that heat if formation of `NH_(3)` is -45 kJ So, `(1)/(2) N_(2(G)) + (3)/(2) H_(2(g)) rarr NH_(2(g)), Delta H = - 45kJ` So, `-45 = (3)/(2) (H - H) + (1)/(2) (N -= N) - 3 (N - H)` `(3)/(2) (435) + (1)/(2) (N -= N) - 3(390)` `N -= N = 945` From the given CONDITION `945 = 1000 - (x^(2) + x + 25)` So, `x^(2) - x + 25= 55`, On solving x = 6S