Question

05 Question (2points) e See page 404 Use the average bond energies in the text to estimate the enthalpy changes of the following reactions. 2nd attempt Part 1 (1 point) See Periodíc Table See Hint N, (g) + O2 (g) ? 2NO (g) 229 kJ/mol Part 2 (1 point) C(s) + CO2(g) ? 2CO(g) Note: The heat of sublimation of graphite, C(s), is 719 kJ/mol. 69

Answer 1

part1:

Bond energies of the reactants:

N?N: 942 kJ/mol
O=O: 494 kJ/mol

Bond energies of the products:

N=O: 607 kJ/mol
N=O: 607 kJ/mol

?H°rxn= ?BE_reactants - ?BE_products

?H°rxn= (942 + 494) - (2 x 607)

?H°rxn= 222 kJ/mol

part2:

C(s)+CO2(g) ->2CO(g)

?H° = 2?Hf° (CO)-DHf° (C)- ?Hf° (CO2)

= (2 moles)x(- 110.52 kJ/mole) – (1 mole)x(0 kJ/mole)- (1 mole)x(-393.51 kJ/mole)

= +172.47 kJ