Thermodynamics Flashcards
What is electron affinity?
Enthalpy change when 1 mole of gaseous atoms form 1 mole of negative ions - atoms and ions in the gaseous state
Why would a gaseous element have a higher entropy value than a solid element?
A gas is more disordered/free to move around
What is the Gibbs free energy change equation?
Delta G = Delta H - TDelta S
What value must Delta G be for a reaction to be feasible?
Delta G must be less than or equal to 0
Why might an entropy change have a positive value?
An increase in the number of particles
Becomes more disordered
Why are some reactions spontaneous?
Entropy change is positive, Enthalpy change is negative so Gibbs free energy is positive
How do you work out the value of entropy change
Sum of entropy products minus sum of entropy reactants (Divided by 1000 if putting into Gibbs free energy equation)
What is the perfect ionic model?
Ions are perfect spheres, only electrostatic attraction, no covalent interaction, only ionic bonding
Why do lattice enthalpies vary?
Size of ion
Charge of ion
What is ionisation energy?
When 1 electron is removed from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous ions with a 1+ charge
What is enthalpy of atomisation?
Enthalpy change when 1 mole of gaseous atoms is formed from the element in its standard state
What is bond dissociation enthalpy?
Enthalpy change when 1 mole of covalent bonds is broken into 2 gaseous atoms
What is lattice dissociation?
Enthalpy change to separate 1 mole of an ionic substance into its ions, forms ions in the gaseous state
What is enthalpy of hydration?
Enthalpy change when 1 mole of gaseous ions become aqueous ions
What is enthalpy of solution?
Enthalpy change when 1 mole of an ionic substance dissolves in a large enough amount of water to ensure that the dissolved ions do not interact