Use bond energies to estimate the enthalpy change for the reaction of one mole ofCH₄ with chlorine gas to give CH₃Cl and hydrogen chloride. BE(C-H) = 414 kJ/mol
BE(C-Cl) = 326 kJ/mol
BE(H-Cl) = 432 kJ/mol
BE(Cl-Cl) = 243 kJ/mol

Question

Quizplus · Accepted Answer

First, we need to write out the balanced equation for the reaction: CH₄ + Cl2 → CH₃Cl + HCl Next, we need to calculate the bond energy changes for each bond broken and formed in the reaction: Breaking bonds: 4 C-H bonds x 414 kJ/mol = 1656 kJ/mol 1 Cl-Cl bond x 243 kJ/mol = 243 kJ/mol Forming bonds: 3 C-Cl bonds x 326 kJ/mol = 978 kJ/mol 1 H-Cl bond x 432 kJ/mol = 432 kJ/mol Now, we can calculate the overall bond energy change for the reaction: ΔH = (energy required to break bonds) - (energy released by forming bonds) ΔH = (1656 kJ/mol + 243 kJ/mol) - (978 kJ/mol + 432 kJ/mol) ΔH = -186 kJ/mol Note that the value is negative, indicating that the reaction is exothermic (releasing heat). Therefore, the correct answer is A) -101 kJ/mol, which is the closest choice.

Use Bond Energies to Estimate the Enthalpy Change for the Reaction