Use the bond energies provided to estimate ? r H° for the reaction below. XeF 2 +2F 2 ? XeF 6 ? r H°= ?
Bond Bond Energy (kJ mol -1 )
Xe-F 147
F-F 159
A) -429 kJ mol -1
B) +159 kJ mol -1
C) -660 kJ mol -1
D) +176 kJ mol -1
E) -270 kJ mol -1

Question

Use the bond energies provided to estimate ? r H° for the reaction below. XeF 2 +2F 2 ? XeF 6 ? r H°= ?
Bond Bond Energy (kJ mol -1 )
Xe-F 147
F-F 159
A) -429 kJ mol -1 
B) +159 kJ mol -1 
C) -660 kJ mol -1 
D) +176 kJ mol -1 
E) -270 kJ mol -1

Quizplus · Accepted Answer

To calculate Δ_rH°_{, we need to use the bond energies provided to calculate the bond energies of the reactants and products. Then we can calculate the energy change of the reaction and use that along with the temperature to find Δ_rH°.

Reactants:
Xe-F (12 bonds) = 12 x 147 kJ mol^-1 = 1,764 kJ mol^-1
F-F (2 bonds) = 2 x 159 kJ mol^-1 = 318 kJ mol^-1}2F₂ (1 bond) = 95 kJ mol^-1 Products: Xe-F (16 bonds) = 16 x 147 kJ mol^-1 = 2,352 kJ mol^-1 ₂ (1 bond) = 266 kJ mol^-1 XeF6 (1 bond) = energy not given Total energy change of reaction: (2,352 kJ mol^-1 + 266 kJ mol^-1) - (1,764 kJ mol^-1 + 318 kJ mol^-1 + 95 kJ mol^-1) = 441 kJ mol^-1 Now we can use the formula: Δ_rH°_{= ΔH1U1B1r} / T Assuming a temperature of 298 K, we get: Δ_rH°_{= 441 kJ mol^-1 / 298 K = -1476 J K^-1 mol^-1 = -270 kJ mol^-1

Therefore, the best choice is E (-270 kJ mol^-1).}

Use the Bond Energies Provided to Estimate ?rH° for the Reaction

Use the Bond Energies Provided to Estimate ?_rH° for the Reaction