entropy and enthalpy Flashcards
give the definition for lattice enthalpy
the energy released when one mole of an ionic compound/lattice is formed from its gaseous ions
define enthalpy change of formation
the enthalpy change when 1 mole of a compound is formed from its elements in their standard states
are lattice enthalpies exothermic or endothermic and why?
exothermic - involves the formation of bonds which releases energy
is enthalpy change of formation endo or exothermic
can be both
define enthalpy change of atomisation
the energy required to form 1 mole of gaseous atoms from an element in its standard state
is enthalpy change exo or endo thermic
always endothermic
define enthalpy change of first ionisation energy
the energy required to remove 1 mole of electrons from one mole of gaseous atoms to form 1 mole of gaseous ions with a +1. charge
is enthalpy change of first ionisation energy exo or endothermic
endothermic
define enthalpy change of second ionisation energy
the energy required to remove 1 mole of electrons from one mole of gaseous ions with a 1+ charge to form 1 mole of gaseous ions with a 2+ charge
define enthalpy change of first electron affinity
energy released when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a 1- charge
is enthalpy change of electron affinity endo or exo
exothermic
define enthalpy change of second electron affinity
the enthalpy change when 1 mole of gaseous ions gain 1 mole of electrons to form 1 mole of gaseous ions with a 2- charge.
what is the order for constructing a born harber cycle
enthalpy change formation —–>
enthalpy change of atomisation —> enthalpy change lattice enthalpy –>
enthalpy change electron affinity
define enthalpy change of solution
the enthalpy change when one mole of an ionic compound dissolves in water
is enthalpy change of solution endo or exothermic
endothermic - breaking bonds
define enthalpy change of hydration
energy released when one mole of gaseous ions dissolves in water
is enthalpy change of hydration exo or endo
exothermic
how do u calculate enthalpy change of solution
- (lattice enthalpy) + (enthalpy change of hydration)
what are the 2 factors affecting lattice enthalpy
charge and ionic radius
what is entropy
measure of disorder in a system,
highly disordered = high entropy
as temperature increases what happens to entropy
increases, as particles have higher energy so become more disordered
how do u calculate entropy change
(sum of products) - ( sum of reactants)k
what are the limitations of predictions made by delta G
rate is very slow as high activation energy
non standard conditions may be used
what is the definition for standard entropy of a substance
the entropy of 1 mol of a substance in JK-1 mol-1 under standard conditions (1 atm 298K)