Lattice enthalpy Flashcards
What is lattice enthalpy?
The enthalpy change when 1 mole of an ionic solid is formed from its gaseous ions under standard conditions
What is the equation for lattice enthalpy?
M⁺(g) + X⁻(g) -> MX(s)
What is the value for lattice enthalpy?
Negative as only involves formation
What enthalpy changes are used to calculate lattice enthalpy?
Enthalpy chance of formation (ΔfH), enthalpy change of atomisation (ΔatH), first ionisation energy (Δie1H) and first electron affinity (Δea1H)
What is enthalpy of atomisation?
The enthalpy required to produce 1 mole of gaseous atoms from the element in its standard state
What an example equation for enthalpy change of atomisation?
1/2O₂(g) -> O(g)
What is the value for enthalpy change of atomisation?
Positive as only breaking bonds
What is first electron affinity?
The energy change that takes place when 1 electron is added to each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1⁻ ions
What is the equation for first electron affinity?
X(g) + e⁻ -> X⁻(g)
What is the value for first electron affinity?
Negative, as nuclear attraction is stronger than repulsion
What is the value for first electron affinity?
Negative, as nuclear attraction is stronger than repulsion
What is the value for the subsequent electron affinities?
Positive as added to the negative ion, so is repeated
What does size of lattice enthalpy show?
The strength of electrostatic attraction between ions in the solid compound due to lattice enthalpy being the energy released on forming ionic bonds
What are 2 ways of making compounds from its elements?
Experimentally and theoretically
What is the experimental method?
Using the associated enthalpy change of formation
