Chemistry - Equilibria, Energetics and Elements - F325 - Energy (2) Flashcards
Define lattice enthalpy.
Lattice enthalpy is the enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions.
Is lattice enthalpy an exothermic or endothermic change?
Lattice enthalpy is an exothermic change.
What does Hess’ law state?
Hess’ law states that if a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.
Define the standard enthalpy change of formation.
The standard enthalpy change of formation is the enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.
Define the enthalpy change of atomisation.
The enthalpy change of atomisation is the enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state.
Is atomisation an exothermic or endothermic reaction?
Atomisation is always an endothermic reaction; bonds are being broken.
Define the first ionisation energy.
The first ionisation energy is the enthalpy change accompanying the removal of one electron from each atom in one mole of gaseous atoms to give one mole of gaseous 1+ ions.
Define the second ionisation energy.
The second ionisation energy is the enthalpy change that accompanies the removal of one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
Define the first electron affinity.
The first electron affinity is the enthalpy change accompanying the addition of one electron to each atom in one mole of gaseous atoms to form one mole of gaseous 1- ions.
Define the second electron affinity.
The second electron affinity is the enthalpy change accompanying the addition of one electron to each ion in one mole of gaseous 1- ions to form one mole of gaseous 2- ions.
Where do elements always sit in Born-Haber cycles?
Elements always sit on the zero line in Born Haber cycles.
Define the standard enthalpy change of solution.
The standard enthalpy change of solution is the enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions.
Define the standard enthalpy change of hydration.
The standard enthalpy change of hydration is the enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions.
What are the two factors that govern the size of lattice enthalpy?
Ionic size and ionic charge are the two factors that govern the size of lattice enthalpy.
As the ionic radius increases, what happens to the lattice enthalpy?
As the ionic radius increases, the attraction between the ions decreases and the lattice enthalpy becomes less negative.