enthalpy changes and born haber module 5 Flashcards
what is enthalpy change of formation
when 1 mole of a compound is formed from its elements
what is enthalpy change of atomisation of an element
1 mole of gaseous atoms formed from an element
what is the enthalpy change of atomisation of a compound
1 mole of a compound is converted to gaseous atoms
what is the First ionisation energy
energy needed to remove 1 mole of electrons from 1 mole of gaseous 1+ ions
what is the second ionisation energy
energy needed to change 1 mole of gaseous 1+ ions into 1 mole of gaseous 2+ ions
what is the 1st electron affinity
energy needed to change 1 mole of gaseous atoms into 1 mole of gaseous 1- ions
what is the 2nd electron affinity
energy needed to change 1 mole of gaseous 1- ions into 1 mole of gaseous 2- ions
what is lattice enthalpy
enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions
what is the enthalpy change of hydration
enthalpy change when 1 mole of gaseous ions is dissolved in water
what is the enthalpy change of solution
enthalpy change when 1 mole of solute is dissolved in a solvent e.g water
what factors affect enthalpy of hydration
ionic charge and ionic radius
smaller ions and higher charge = better at attracting water molecules
what is entropy
a measure of disorder in a system/dispersal of energy in a system
what happens to entropy as you go from a solid to a gas
it increases
how do you calculate the entropy of a system
entropy of products - entropy of reactants
what is free energy change used to predicf
whether a reaction is feasible
what types of reactions are feasible
only exothermic
why might a reaction still not be feasible even if it is exothermic
might have a really high activation energy or slow rate of reaction
how does ionic charge affect lattice enthalpy
Higher the charge , the stronger the electrostatic attraction so more energy is released when the ionic lattice is formed which means it is more negative
how does ionic radius affect lattice enthalpy
smaller ionic radii = higher charge density and more electrostatic attraction makes it more exothermic
how
how does ionic charge affect the enthalpy of hydration
Higher charge = Higher enthalpy of hydration
better at attracting water molecules and more energy is released when bonds are made which is more exothermic
