Entropy And Free Energy Flashcards
How to explain if A reaction is feasible?
Enthalpy change is not sufficient to explain whether a reaction is feasible or not we must instead consider the change in free energy
For example ammonium nitrate dissolving in water is endothermic and sodium hydroxide dissolving in water is exothermic but are both feasible above 20 degrees
What is entropy?
A measure of disorder
A reaction is favoured if entropy increases (>0)
What is standard entropy?
The amount of entropy in one mole of the substance under standard conditions
Entropy in solids, liquids and gases?
The particles In a solid move about fixed positions-little entropy
Particles in liquids are able to move past each other changing speed and direction
Particles in gas move much faster and change direction much more - greatest entropy
Entropy equation?
Entropy= products - reactants
Determine feasible?
A reaction for which free energy < 0
When is a dynamic equilibrium established?
When free energy is equal to 0
What is the free energy equation?
Free energy = lattice enthalpy - temperature x entropy
What unit’s is temperature in?
Kelvin
To convert degrees to Kelvin add 273
How do you calculate the temp at which a reaction becomes feasible?
T= lattice enthalpy/ entropy
What are the units used for lattice enthalpy and entropy
Enthalpy = KJmol-1
Entropy = JK-1mol-1
*/. 1000 -> KJ-1mol-1
