Entropy & Free Energy
- Created by: annaeb
- Created on: 10-05-21 21:04
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- Entropy & Free Energy
- factors affecting lattice enthalpy
- size of the ion/ ionic radius
- as the charge of the ion increases, the value of the lattice enthalpy becomes less exothermic
- because there's less attraction between ions
- the larger the ion, the smaller the charge density
- as the charge of the ion increases, the value of the lattice enthalpy becomes less exothermic
- size of the ion/ ionic radius
- entropy
- tells you how much disorder there is
- gases have the most disorder- have the highest entropy
- solids have the least disorder/ more order- lowest entropy
- calculating entropy changes
- ^S= S products- S reactants
- tells you how much disorder there is
- free energy change
- ^G=^H-T^S
- T= ^H/ ^S
- measure used to predict whether a reaction is feasible
- if ^G is - or = 0, reaction is feasible
- effect of temperature
- if a reaction is endothermic with ^S= -, ^G= +
- reactions not feasible at any temp.
- reaction is exothermic, with ^S= +, ^G= -
- reactions = feasible at any temp.
- ^H =+, ^S= +, reaction only feasible at certain temps.
- if a reaction is endothermic with ^S= -, ^G= +
- ^G=^H-T^S
- factors that affect the enthalpy of hydration
- ionic charge
- as charge increases, value of enthalpy of hydration becomes more exothermic
- due to increased attraction between ions & water molecules
- size of the ion
- as ionic radius increases, enthalpy of hydration becomes less exothermic
- the larger the ion, the smaller the charge density
- less attraction between ions & water molecules
- ^H hyd of Mg 2+ = more exothermic than Ca2+
- Mg2+ has a larger ionic radius & greater charge density
- greater attraction between Mg2+ & water molecules
- Mg2+ has a larger ionic radius & greater charge density
- ionic charge
- factors affecting enthalpy change of solution
- temperature
- affects entropy of system
- at 0, solids have 0 entropy, solid heated up to gas, substance has increasing entropy
- dissolving
- entropy increases
- producing gases
- metal + acid -entropy increases (H2 being produced)
- temperature
- factors affecting lattice enthalpy
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