Thermodynamics Flashcards
Define standard enthalpy of formation
The enthalpy change when one mole of a compound is formed from its elements under standard conditions with all reactants and produce in standard states
Define standard enthalpy of combustion
The enthalpy change one one mole of compound is completely burned in oxygen under standard conditions with all reactants and products in their standard states
Define mean bond enthalpy
The enthalpy change when one mole of gaseous molecules each break a covalent bond to from two free radicals, averaged over a range of compounds
Define first ionisation enthalpy
The standard enthalpy change when one mole of electrons is removed from one mole of gaseous atoms to give one mole of gaseous ions each with a single positive charge
Define second ionisation enthalpy
The standard enthalpy change when one mole of electrons is removed from one mole of gaseous +1 ions to give one mole of gaseous ions each with a +2 charge
Define standard enthalpy of atomisation
The enthalpy change when one mole of gaseous atoms if formed from an element in its standard state
Define first electron affinity
The standard enthalpy change when one mole of electrons is added to a mole of gaseous atoms to form a mole of gaseous ions with a 1- charge
Define second electron affinity
The standard enthalpy change when one mole of electrons is added to a mole of gaseous ions each with single negative charge to form a mole of gaseous ions with a 2- charge
What is the relationship between enthalpy of atomisation and bond enthalpy.
enthalpy of atomisation is double bond enthalpy
Define lattice formation enthalpy
The standard enthalpy change when one mole of solid ionic compound is formed from its gaseous ions
Define lattice dissociation enthalpy
The standard enthalpy change when one mole of solid ionic compound dissociates into its gaseous ions
What type of reaction is lattice enthalpy of dissociation?
Endothermic
What type of reaction is lattice enthalpy of formation?
Exothermic
What are the three factors affecting the strength of ionic bonding?
- Charge of ions
- Radius of ions
- Attraction between ions
What is covalent character?
Positive ion polarises the negative ion by attracting some of its electron density
What is the perfect ionic model?
Ions are perfect spheres, as point charges. Ions can’t be polarised.
Define standard enthalpy of solution
The standard enthalpy change when one mole of solid ionic compound dissolves to form its aqueous ions
Define standard enthalpy of hydration
The standard enthalpy change when one mole of gaseous ions is converted into one mole of aqueous ions
Show standard enthalpy of formation for NaCl.
Na(s) + 1/2Cl2(g) -> NaCl(s)
Show first ionisation of Ca
Ca(g) -> Ca+(g) + e-
Show standard enthalpy of atomisation for Br.
1/2Br2(l) -> Br(g)
Show mean bond enthalpy for Br.
Br2(l) -> 2Br(g)
Show lattice formation enthalpy for MgBr2
Mg2+(g) + 2Br-(g) -> MgBr2(s)
Show first electron affinity of O
O(g) + e- -> O-(g)
Show lattice dissociation enthalpy for MgBr2
MgBr2(s) -> Mg2+(g) + 2Br- (g)
Show standard enthalpy of hydration for Cl
Cl-(g) -> Cl-(aq)
Show standard enthalpy of solution for NaCl
NaCl(s) -> Na+(aq) + Cl-(aq)
