Topic 13 - Further Enegetics Flashcards
Define Lattice Energy
Enthalpy change when one mole of ionic solid is formed from its gaseous ions in standard conditions
Define Enthalpy change of atomisation
Enthalpy change when one mole of gaseous atoms are formed from its elements
Define electron affinity
Energy change when each atom in one mole of atoms in gaseous state gains an electron
How does polarisation increase?
A cation with a high charge and small radius has large polarising power and anions with large charge and large radius are polarised most easily
Define enthalpy change of solution
Enthalpy change when one mole of ionic solid dissolves in water to form an infinitely dilute solution
Define enthalpy change of hydration
Enthalpy change when one mole of an ion in its gaseous state is completely hydrated by water
Factors affecting the magnitude of the hydration enthalpy
Doubly charged ion has stronger interaction wit water molecules so electrostatic force of attraction between doubly charged ion and water molecule will be greater than between singly charged ion
As go down the group the magnitude of enthalpy of solution becomes less negative as ions get larger so electrostatic force of attraction is weaker
What is a spontaneous processes
One that takes place without continuous intervention
Freezing of water to form ice - water in -20 then turn to ice
Intervene to reverse the reaction - never happens on its own
What is entropy
Property of matter that is associated with the degree of disorder of the particles - second law of thermodynamics
If two gases form a solid then reduction in entropy
Total entropy increases for spontaneous reaction
Total entropy change =
Entropy of system + entropy of surroundings
Entropy change is the system =
Total entropy of products - total entropy of reactants
Entropy change of the surroundings =
-DeltaH / T
