Chapter 22 Flashcards
Lattice enthalpy 🔺LEH
The enthalpy change that accompanies the formation of 1 mole of an ionic compound from its gaseous ions under standard conditions.
It is an exothermic change
Standard enthalpy change of formation 🔺fH
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.
This is exothermic
Standard enthalpy change of atomisation 🔺atH
The enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state.
Always endothermic
First ionisation energy 🔺IEH
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.
Always endothermic
First electron affinity 🔺EAH
The enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of gaseous 1– ions.
Always exothermic
Second electron affinity
Second electron affinities are endothermic. a second electron is being gained by a negative ion which repels the electron away. so energy must be put in, to force the negatively charged electrons onto the negative ion
standard Enthalpy change of hydration
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
entropy
The used for the dispersal of energy and disorder within the chemicals making up the chemical system.
Standard entropy
The entropy of one mole of a substance, under standard conditions (100kpa + 298K)
Units JK^-1mol^-1
Entropy change of a reaction ΔS
Sum of entropy of products - Sum of entropy of reactants
free energy change ΔG
The balance between enthalpy, entropy and temperature for a process
given by ΔG = ΔH – TΔS. A process is feasible when ΔG < 0.
standard enthalpy change of solution
The enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions
