Question

Objective Knowledge Check Question 5 Calculate the heat of reaction AH for the following reaction: 2 NHỊg)ẠN,(g) + 3H5(g) You can find a table of bond energies by using the Data button on the ALEKS toolbar. Round your answer to the nearest kJ/mol.

Answer 1

it N-N triple H2 H-H bond Head of the reaction or enthalpy of a reaction is the amount of energy released or absorbed in a reaction at constant presswazi Energy released or absorbed is determined by the energy difference between reactant and product. Energy of reactant and product is governed by the lond energies of the bonds which makes reactants and products. The given reaction is 21113 (G) — N, CH) + 3H2(g) Bonds invohed:- 2%(3 W-H bond) — I N-N bond + 344-H bond) WH₂ N2 3 N-H ->N NEN single bond it I H I Bonds Bond energies (kJ/mol) O NEN 941 | H-1 single ☺N-H bond © H-H 436 This values are standard bond energy values, can be found in ALEKS toolbar. So energy absorbs (bonds broken) =2x3 x N-H = 68391 kJ energy released (bonds formed) = 1XNzr + 3x H-H = 1 X941 + 3x436 KI = 941+ 1308 kJ = 2249 KI So overall energy change - ( 2346– 2249) 47 = 97KI 391 = 2346 kJ

:. 4H=97 KJ /mol As it is positive, the reaction is endothermie.