MDCAT Chemistry MCQ #1753

In the Born-Haber cycle for NaCl, sublimation is +108, IE is +496, Cl dissociation is +242, EA is -349, and Lattice Energy is -787. Calculate dHf.

MDCAT Chemistry MCQ #1753

  1. Question 1

    Q1. In the Born-Haber cycle for NaCl, sublimation is +108, IE is +496, Cl dissociation is +242, EA is -349, and Lattice Energy is -787. Calculate dHf.

    • A) -411
    • B) +411
    • C) -311
    • D) -811

    Answer: -411

    Explanation: dHf = Sublimation + IE + 0.5*Dissociation + EA + Lattice Energy. (108+496+121-349-787) = -411. +411 incorrectly assumes an endothermic overall process.