1.

Consider the following data: Delta_(f) H^(2) (N_(2)H_(4), l) =50kJ//mol,, Delta_(f) H^(@) (NH_(3), g)=-46 kJ//mol, B.E. (N-H)= 393kJ//mol and B.E. (H-H)= 436 kJ/mol, also Delta_("vap") H (N_(2)H_(4),l)= 18kJ//mol. The N-N bond energy in N_(2)H_(4) is

Answer»

226 kJ/mol
154 kJ/mol
190 kJ/mol
45.45 K Cal/mole

Solution :`N_(2) + 2H_(2) rarr N_(2)H_(4(l)), Delta H_(1) = 50`
`(1)/(2) N_(2) + (3)/(2) H_(2) rarr NH_(3(g)), Delta H_(2) = - 46`
`UL(N_(2)H_((l)) rarr N_(2)H_(4(g)), Delta H_(3) = 18)`
`N_(2)H_(4(g)) + H_(2) rarr 2NH_(3) , Delta H`
`Delta H = - Delta H_(3) + 2 Delta H_(2) - Delta H_(1) = - 160`
Theoretically, `Delta H = ((N-N) + 4(N -H) + (H - H)) - (2 xx 3 xx (N-H))`
`rArr (N-N) = 190` kJ/mol = 45.45 Kcal/mole


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