Topic 13
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What is standard lattice energy?
• The energy change of a compound • When one mole of ionic solid is formed • From its gaseous ions • UNDER STANDARD CONDITIONS (298K + 100kPa)
What Factors affect lattice energy?
Factors that increase lattice energy • The higher charge • More Cation-Anion[-Cation] interactions • The high ionic radii/ion size
What is the standard enthalpy of atomisation?
• Enthalpy change when measured at • Standard conditions (298K 100kPa) • For one mole of gas to be produced from its element in its natural state
What is electron affinity?
• The energy change • When each atom in one mole of atoms • In a gaseous state • Gains an electron to form an ion
What is the born harbour cycle?
A cycle that shows the energy changes in a reaction such as: • Enthalpy change of formation • Enthalpy change of atomisation • First ionisation energy • Electron Affinities • Lattice Energy of Ionic Lattice
What are the steps for constructing a Born-Haber cycle?
What is the relationship between the theoretical and the experimental lattice energy values?
Theoretical values will always be higher than the experimental values because we assume: • The ions are in contact with each other • Ions are perfectly spherical • There is an even distribution of charge and no covelent characteristics
Why is there covalency in the ionic bond?
• The cation (+) attracts the electrons on the anion (-) • This pulls them towards the cation distorting the electron density of the anion • Meaning the Cation POLARISES the Anion
Why does polarisation happen between ions?
• Cation (+) attracts the elections on the Anion (-) • This pulls the electron towards the cation • Distorting the electron density of the Anion • Meaning the Cation polarises the Anion
What are Fajan’s Rules?
Polarisation is increased: - The high charge density of the Cation - An Anion with a high charge and big size
Explain this diagram
• The high charge density of the Cation • An Anion with a high charge and big size
What it the definition of enthalpy change of solution?
• Determines solubility • The enthalpy change when • One mole of ionic solid dissolves in water • Forming an infinitely dilute solution Made up from enthalpy of dissociation and hydration
What is indefinite dilution?
• In dilution ions in a solution move apart (Endo) • Ions also become Hydrated (Exo) • The Exo and Endo processes affect the enthalpy change of solution referring to an infinitely dilute solution • Where after a certain point the value won’t be affected by further dilution
What is the definition of enthalpy change of hydration
• The enthalpy change • When one mole of an ion is in a gaseous state • Is completely hydrated by water
What are the calculations involving the enthalpy of hydration and enthalpy of the solution?
What is the effect of ionic charge on the enthalpy of hydration?
• The higher the charge • The The higher the forces of attraction between the ion and the water molcules
What is the effect of ionic radii on the enthalpy of hydration?
• An increase in ionic radius • Leads to bigger ions • With less electrostatic force of attraction between ions and water molecules • Meaning the energy released upon hydration decreases
What is entropy?
The measure of the degree of disorder or randomness of a system A system is any chemical situation
What happens to entropy when the state changes?
• The disorder increases when going from a solid to a liquid • The disorder decrease when going from a gas to a liquid
What happens to entropy when dissolving a solid lattice?
• The disorder increases when a solid dissolves • Meaning an increase in the entropy
What happens to entropy when there is a change in the number of moles
• The disorder increases when the number of moles increases • The disorder decreases when the number of moles decrease
What is the formula for total entropy change?
What is the formula for entropy change in the system?
What is the formula for entropy of the surroundings?
