Heat of formation of 2 moles of `NH_(3)(g) " is" -90 kJ`l 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

6

Explanation

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