Given the bond enthalpies of N N is 946 ~kJ / mol . H - H is 435 ~kJ / mol , N - N is 159 ~kJ / mol and N - H is 389 ~kJ / mol , heat of formation of hydrazine in the gas phase (in kJ / mol ) is

Step-by-step solution

The reaction to form hydrazine is as follows N ₂(g)+2 H - H ( ~g ) N ₂ H ₄(g) aligned _r H^ = _f H^ ( N ₂ H ₄ )= BE ( reactant ) - BE (product) aligned aligned =[B E(N N+ & 2 B E (H-H)] -[B E(N-N)+4(B E)(N-H)] aligned aligned & =[946+2(435)]-[159+4 389] & =101 ~kJ / mol aligned