1.8 Thermodynamics Flashcards
What is the definition of Enthalpy Change?
Change in heat energy at constant pressure
What are standard conditions?
298 K and 100kPA
What is Hess’ law?
That enthalpy change is independent to route taken
What is the definition of mean bond dissociation?
Enthalpy change
To break bonds in a gaseous molecule
Averaged over a range of compounds
Why are given values of Mean bond dissociation not the same as experimental values?
It’s averaged over a range of compounds and not specific to the bond
What is the definition of enthalpy of atomisation?
Enthalpy change
To form 1 mole of gaseous atom
From its element in its standard state
What is the definition of electron affinity?
Enthalpy change
To form 1 mole of gaseous -1 ions
From 1 mole of gaseous atoms
What is the definition of ionisation energy?
The enthalpy change
To form 1 mole of gaseous +1 ions from 1 mole of gaseous atoms
What is the definition of enthalpy of formation?
The enthalpy change
To form 1 mole of a substance
With all substances in their standard states
What is the definition of enthalpy of combustion?
The enthalpy change
To combust 1 mole of a substance in excess O2
With all substances in their standard states
What is the definition of enthalpy of hydration?
The enthalpy change
To form 1 mole of aqueous ions
From 1 mole of gaseous ions
What is the definition for enthalpy of lattice formation?
The enthalpy change
To form 1 mole of solid ionic compound
From its gaseous ions
What are the main problems with the energetics required practical?
Heat loss
Incomplete combustion when using calorimeter
What is the relationship between bond dissociation and enthalpy of atomisation?
Atomisation is half bond dissociation
What are the two ways of finding lattice enthalpy?
Born Haber cycles
Perfect ionic model
