Thermodynamics Flashcards
What is Bond Dissociation
Change in Enthalpy when 1 mol of gaseous molecules each break a covalent bond to form 2 free radicals
I2(g) -> 2I (g)
Endothermic
What is Enthalpy of Atomization
Change in Enthalpy when one mole of gaseous atoms are formed from an element in its standard states under standard conditions
1/2 I2(s)-> I(g)
Endothermic
What is 1st Ionisation Enthalpy
Enthalpy change when One mole of gaseous atoms converted into one mole of gaseous ions each with a single positive charge under standard conditions
Mg(g) ->Mg+ +e-
Endothermic
What is the 2nd ionisation energy
is it endo or exothermic
One mole of gaseous atoms with single positive charges converted into one mole of gaseous ions each with a +2 positive charge under standard conditions
Mg+(g) ->Mg2+ +e-
Endothermic
What is Enthalpy of Formation
Exo or Endo?
The enthalpy change when 1 mol of a compound is formed from its element in their standard states under standard conditions
2Na(s) +O2(g) -> Na2O(s)
Exothermic
What is Enthalpy of combustion
Exo or Endo?
The Enthalpy change when 1 mol of a substance is completely burnt in oxygen under standard conditions with all reactants and products are within their standard state.
H2(g) + O2(g) -> H2O(g)
Exothermic
what is the 1st electron affinity
Exo or Endo?
Enthalpy change when 1 mol of gaseous atoms is converted into one mole of gaseous ions with a single negative charge by each gaining an electron
I(g)+e- -> I-(g)
Exothermic
what is the 2nd electron affinity
Change in enthalpy when 1 mol of gaseous ions with single negative charges gain 1 e- to form a mol of gaseous ions each with a -2 charge
S-(g) +e- -> S2-(g)
Endothermic
what is Lattice Enthalpy of Formation
Exo or Endo?
Standard enthalpy change when 1 mol of an ionic compound is formed from its gaseous ions under standard conditions
2Al3+(g) +3O2-(g) -> Al2O3(s)
Exothermic
What is Lattice Enthalpy of dissociation
Standard enthalpy change when 1 mol of an ionic compound is completely dissociated into its gaseous ions under standard conditions
MgBr2(s) -> Mg2+(g) +2Br- (g)
Endothermic
What is Standard enthalpy of Hydration
Exo or Endo?
The standard enthalpy change when water molecules surround 1 mol of gaseous ions
Exothermic
Na+(g) + (aq) -> Na+(aq)
What is Standard Enthalpy of Solution
The standard enthalpy change when one mole of solute completely dissolves in sufficient solvent, to form a solution in which no further enthalpy change takes place upon further dilution
NaCl(s) +(aq) -> Na+(aq) + Cl-(aq)
Name then Enthalpy Change :
I2(g) -> 2I- (g)
Endothermic
Bond Dissociation
Name the enthalpy change:
1/2 I2(s)-> I(g)
Endothermic
Enthalpy of Atomisation
Name the Enthalpy Change:
Mg(g) ->Mg+ +e-
Endothermic
1st Ionisation Enthalpy
Name the Enthalpy Change:
Mg+(g)->Mg2+(g) +e-
2nd Ionisation Energy
Name the Enthalpy Change:
2Na(s) +O2(g) -> Na2O(s)
Exothermic
Enthalpy of Formation
Name the Enthalpy Change:
H2(g) + O2(g) -> H2O(g)
Exothermic
Enthalpy of Combustion
What is Mean Bond Enthalpy?
Enthalpy Change when 1 mol f gaseous molecules each breaks a covalent bond to form two free radicals under standard conditions.
This value is averaged over a range of molecules.
What is Entropy?
measure of disorder in a system
Number of ways energy can be shared between particles
More Disorder = Higher Entropy Levels
What is Gibbs Free Energy?
usable energy that is available to do work
Indicates the feasibility of a reaction at a given temperature
How do you calculate Enthalpy of Solution?
Lattice Dissociation Enthalpy + Sum of all Enthalpy of Hyrdation
The Perfect Ionic Model States that:
1) Ions are perfectly Spherical
2) The Charge and electron density is Evenly Distributed
A Larger Discrepancy in Theoretical Lattice Enthalpy Data shows
More covalent character in the molecule.
The positive ion distorts the charger distribution more which polarises the negative ion slightly
Higher Metal charges produce more discrepancy
Explain why does the Enthalpy of hydration decrease as you go down group 1
As you go down the group the atomic radius decreases, less attractive forces between bonding electrons and nucleus.
Less strong electrostatic attraction between the positive ion and the delta negative constituents of the surrounding water molecules
