Question

Use the molar bond enthalpy data in the table to estimate the value of AHixn for the equation Average molar bond enthalpies. (Hbond) kJ · mol-1 NH2(g) + 2O2(g) — HNO2(g) + H2O(g) Bond CON 464 Bond 0-H 0-0 C-O kJ mol-1 890 390 201 N-H The bonding in the molecules is shown. N-O O=O 142 351 502 730 418 + + C=O N=N N=0 F-F 607 347 155 615 243 A Hinc C-C C=C CEC C-H AHxn = C1-C1 Br-Br H-H 811 414 192 435 565 C-F 439 H-F C-ci 331 H-C1 431 C-Br H-Br 368 C-N 276 293 615 H-S S-S 364 225 C=N

Answer 1

Equation: NH3(g) + 20,() — HNO3(8) + H20(8) Bond energy of N-H bond = 390 kJ/mol Bond energy of O =O bond = 502 kJ/mol Bond energy of N-O bond = 201 kJ/mol Bond energy of N=O bond = 607 kJ/mol Bond energy of O-H bond = 464 kJ/mol Number of bonds present in the reactants: 3 N-H and 2 O=0 Number of bonds present in the reactants : 1N = 0, 2N-O and 3 O-H Enthalpy change of the reaction is, AH = Bond energy of rectants – Bond energy of products (1(N=0) = (3(N-H)+2(0=0)) + 2(N-0) + 3(0-H) |(3(390 kJ) +2(502 kJ)) (1(607kJ) +2(201kJ) +3(464 kJ)) = -227 kJ