thermodynamics

• What is the definition of enthalpy change of formation?

  Change when one mole of compound forms
• What is an example of enthalpy change of formation?

  Formation of ether from carbon and hydrogen
• What is lattice enthalpy of formation?

  Change when solid ionic compound forms from gaseous ions
• What is the lattice enthalpy of dissociation?

  Change when solid ionic compound dissociates into gaseous ions
• What does the enthalpy change of dissociation refer to?

  Breaking one mole of bonds in gaseous state
• What is the enthalpy change of first ionization?

  Change when one mole of gaseous 1+ ions forms
• What is enthalpy change of atomization?

  Change when one mole of gaseous atoms forms from an element
• What is the second ionization energy?

  Change when gaseous 2+ ions form from 1+ ions
• What is the first electron affinity?

  Change when gaseous 1- ions form from gaseous atoms
• What is the second electron affinity?

  Change when gaseous 2- ions form from 1- ions
• How can students effectively learn definitions in thermodynamics?

  By practicing cycles and integrating definitions
• What is the purpose of the Born-Haber cycle?

  To calculate lattice enthalpies indirectly
• What is the starting point of the Born-Haber cycle for lithium chloride?

  Solid lithium chloride (LiCl)
• What are the two methods to form lithium chloride in the Born-Haber cycle?

  From elements or from gaseous ions
• What is the enthalpy of atomization of chlorine in the Born-Haber cycle?

  Converts 1/2 Cl2 gas to Cl gas
• What is the first ionization energy of lithium?

  Removal of an electron to form Li+
• What is the electron affinity process for chlorine?

  Adding an electron to form Cl-
• What is the lattice enthalpy of formation in the Born-Haber cycle?

  Formation of LiCl from gaseous ions
• What is the relationship between enthalpy change and the route taken in a Born-Haber cycle?

  Independent of the route taken
• How do you calculate lattice enthalpies using the Born-Haber cycle?

  By applying Hess's law to the cycle
• What is the significance of endothermic and exothermic processes in the Born-Haber cycle?

  Determines energy input or release
• What is the enthalpy of atomization of chlorine divided by two used for?

  To account for 1/2 Cl2 gas to Cl gas
• What is the enthalpy of formation of lithium chloride?

  -409 kJ/mol
• What is the first ionization energy of lithium?

  519 kJ/mol
• Why do we divide the enthalpy of atomization of chlorine by 2?

  Because we are using half a mole of Cl₂
• How do you calculate the enthalpy of atomization for half a mole of Cl₂?

  Divide 242 kJ/mol by 2
• What is the enthalpy change for converting lithium solid to lithium gas?

  161 kJ/mol
• What is the first ionization energy of lithium in the context of lithium chloride formation?

  It is an endothermic process of 519 kJ/mol
• What is the first electron affinity of chlorine?

  -364 kJ/mol
• What does a negative lattice enthalpy indicate about the formation of lithium chloride?

  It indicates an exothermic reaction
• How can you check if your calculated lattice enthalpy is correct?

  Ensure the total around the cycle equals zero
• What happens to the lattice enthalpy when the ionic compound has covalent character?

  It may differ from the theoretical value
• What is the theoretical lattice enthalpy based on?

  A perfectly ionic model of ions
• What does polarization of ions indicate in ionic compounds?

  It indicates some covalent character
• What is the enthalpy change of solution?

  Enthalpy change when one mole dissolves
• What are the steps to calculate lattice enthalpy using a cycle?

  1. Identify start and end points.
  2. Use known enthalpy values.
  3. Adjust signs based on direction.
  4. Ensure total equals zero for verification.
• What is the significance of a positive lattice enthalpy value?

  • Indicates an endothermic reaction
  • Suggests energy is absorbed during dissolution
• What factors affect the difference between theoretical and experimental lattice enthalpies?

  • Ionic character vs. covalent character
  • Size and charge of ions
  • Distortion of electron clouds
• How does the size of ions affect lattice enthalpy?

  • Larger ions lead to greater distortion
  • Greater distortion increases covalent character
• What is the role of electron affinity in ionic compound formation?

  • Measures energy change when an electron is added
  • Influences overall lattice enthalpy calculations