Lesson 13A.1

13A.1 Lattice energy and Born-Haber cycles Quiz: Pearson Edexcel Chemistry, Unit 13

20 questions

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Lesson 13A.1, Lattice energy and Born-Haber cycles: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 13: Energetics II, written with Revision Ninja.

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The 20 questions

  1. What is lattice energy?

    • The energy change when one mole of an ionic solid dissolves in water
    • The energy change when one mole of an ionic solid is formed from its gaseous ions
    • The energy needed to remove one mole of electrons from gaseous atoms
    • The energy change when one mole of gaseous atoms forms one mole of covalent bonds
  2. What sign does the lattice energy of an ionic compound normally have when it is defined as formation from gaseous ions?

    • Positive, because lattice formation always breaks ionic bonds
    • Positive, because energy must be supplied to form a lattice
    • Negative, because energy is released when gaseous ions come together to form a lattice
    • Zero, because lattice formation is neither exothermic nor endothermic
  3. What is the enthalpy change of atomisation?

    • The energy change when one mole of gaseous ions is formed from gaseous atoms by removing electrons
    • The enthalpy change when one mole of gaseous atoms is formed from an element in its standard state
    • The energy change when one mole of electrons is added to one mole of gaseous atoms to form negative ions
    • The energy needed to form one mole of an ionic solid directly from its elements in their standard states
  4. What is the electron affinity of an element?

    • The energy needed to remove one mole of electrons from one mole of gaseous atoms
    • The energy change when one mole of gaseous ions loses an electron
    • The energy change when one mole of ionic solid is formed from its gaseous ions
    • The energy change when one mole of gaseous atoms each gains an electron to form gaseous 1- ions
  5. Which term describes the enthalpy change for forming one mole of an ionic compound from its elements in their standard states?

    • Standard enthalpy change of atomisation
    • Standard enthalpy change of combustion
    • Standard enthalpy change of formation
    • Standard enthalpy change of solution
  6. What does a more exothermic lattice energy indicate about an ionic compound?

    • A stronger ionic bond between the ions in the lattice
    • A greater solubility in water at 298 K
    • A larger electron affinity of the anion
    • A higher melting temperature for every compound regardless of structure
  7. Why can a Born-Haber cycle be used to find an unknown enthalpy change?

    • Hess's law says the sum of enthalpy changes around a closed cycle is zero
    • Every step in the cycle is endothermic, so the total is always positive
    • Enthalpy changes depend on the path taken, so each route must be measured separately
    • Enthalpy changes equal entropy changes, so the cycle must balance
  8. Using dHf(NaCl) = -411, atomisation of Na = +107, first ionisation energy of Na = +496, half the bond energy of Cl2 = +121 and electron affinity of Cl = -349 (all in kJ mol-1), what is the lattice energy of NaCl?

    • +786 kJ mol-1
    • -786 kJ mol-1
    • -375 kJ mol-1
    • -411 kJ mol-1
  9. Why is the lattice energy of MgO much more exothermic than that of NaCl?

    • Mg2+ and O2- have higher charges and smaller radii, so the electrostatic attraction is much stronger
    • NaCl has larger ions and so forms the stronger lattice of the two
    • Mg and O have fewer electrons, so their ions are larger and attract less strongly
    • MgO is covalent, so no lattice energy term applies to it
  10. A Born-Haber cycle for an ionic compound has dHf = -600, atomisation of metal = +150, ionisation energy = +700, half bond energy = +100 and electron affinity = -50 (all kJ mol-1). What is the lattice energy?

    • -300 kJ mol-1
    • -900 kJ mol-1
    • -1500 kJ mol-1
    • +1500 kJ mol-1
  11. The second electron affinity of oxygen is endothermic. Why does O2- still form in an ionic lattice such as MgO?

    • The large lattice energy released when the solid forms more than compensates for the endothermic second electron affinity
    • O2- forms because the second electron affinity becomes exothermic once the oxide ion is surrounded by Mg2+ ions in solution
    • The second electron is removed from the lattice as a free electron, so no net energy is needed for the process
    • Oxygen gains two electrons only at very high pressure, so the enthalpy change for the second electron is negligible
  12. In a Born-Haber cycle for MgCl2, how many chlorine electron affinity terms appear?

    • Two, one for each chlorine atom gaining an electron
    • One, because magnesium only gives one electron
    • Four, because each Cl2 molecule gives four chloride ions
    • Zero, because chloride ions are formed directly from chlorine gas
  13. Which ionic compound has the largest magnitude of lattice energy?

    • KCl, because potassium has a large atomic radius
    • NaF, because fluoride is the smallest halide ion
    • MgO, because its ions carry charges of 2+ and 2- and are small
    • NaCl, because sodium chloride is the most common salt
  14. Which change would make the lattice energy of an ionic solid more exothermic?

    • Raising the temperature of the solid
    • Dissolving the solid in a larger volume of solvent
    • Using ions with lower charges and larger radii
    • Using ions with higher charges and smaller radii
  15. A Born-Haber cycle for CaO has dHf = -635, atomisation of Ca = +178, IE1 + IE2 of Ca = +1735, atomisation of O = +249, EA1 of O = -141 and EA2 of O = +798 (kJ mol-1). What is the lattice energy of CaO?

    • +3454 kJ mol-1
    • -2184 kJ mol-1
    • -635 kJ mol-1
    • -3454 kJ mol-1
  16. What is the experimental lattice energy from a Born-Haber cycle compared with the theoretical ionic value telling us when the experimental value is more exothermic?

    • The compound is a metal, because only metals show more exothermic lattice energies
    • The compound is molecular, so lattice energy does not apply to it
    • The compound is purely ionic, because the experimental value is always exact
    • The bonding has some covalent character, because the ionic model underestimates the attraction
  17. Using dHf(KCl) = -437, atomisation of K = +89, IE of K = +419, half bond energy of Cl2 = +121 and lattice energy of KCl = -701 (kJ mol-1), what is the electron affinity of chlorine?

    • +365 kJ mol-1
    • -1046 kJ mol-1
    • -365 kJ mol-1
    • -701 kJ mol-1
  18. For MgCl2, dHf = -641, atomisation of Mg = +148, IE1 + IE2 of Mg = +2189, bond energy of Cl2 = +242 (for two atoms, 2 x 121), and 2 x electron affinity of Cl = -698 (all kJ mol-1). What is the lattice energy?

    • -2522 kJ mol-1
    • +2522 kJ mol-1
    • -1881 kJ mol-1
    • -641 kJ mol-1
  19. Which statement about lattice energies of the Group 1 halides is correct?

    • LiF and LiI have the same lattice energy, because both contain Li+
    • LiI is more exothermic than LiF, because iodide has more electrons and forms stronger bonds
    • LiI is more exothermic than LiF, because iodide is a stronger base than fluoride
    • LiF is more exothermic than LiI, because the smaller F- ion lies closer to Li+ and is attracted more strongly
  20. A student says lattice energy directly measures how easily an ionic solid dissolves. Which evaluation is best?

    • True, because lattice energy always equals the enthalpy of solution for every ionic solid dissolved in water
    • False, because lattice energy describes ionic bond strength, while solubility also depends on hydration enthalpies
    • True, because a larger lattice energy always means the solid dissolves more readily in any solvent at any temperature
    • False, because lattice energy is positive for all solids, so it cannot be compared with hydration enthalpies at all

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