Physical- Thermodynamics Flashcards
What is entropy?
A measure of disorder
What is the entropy change?
The change in disorder of a system. An increase in disorder produces a positive entropy change
Define Enthalpy of solution
The standard Enthalpy change when one mole of an ionic solid dissolves completely in sufficient water to form a solution in which the ions are far enough apart not to interact with each other
Define the perfect ionic model
A mathematical calculation of the lattice formation Enthalpy of a compound, which assumes that the positive and negative ions are perfectly spherical and that there is no covalent character in the compound
Define Enthalpy of atomisation of an element
The Enthalpy change when one mole of gaseous atoms is formed from the element in its standard state
Define Enthalpy change
The heat change at constant pressure
Define second ionisation energy
The standard Enthalpy change when one mole of gaseous unpositive ions is converted into a mole of gaseous ions each with a double positive charge
State Hess’s law
The Enthalpy change of a reaction depends only on the initial and final states of the reaction and is independent of the route by which the reaction occurs
Define mean bond Enthalpy
The Enthalpy change when one mole of covalent bonds is broken, with all species in the gaseous state (an average over a range of different compounds)
How do you calculate Gibbs Free Energy?
🔺G= 🔺H- T🔺S where G is free energy change, H is Enthalpy change and S is entropy change
Define standard enthalpy of formation
The enthalpy change when one mole of a substance is produced from its constituent elements under standard conditions, all reactants and products being in their standard states
Define standard enthalpy of atomisation of a compound
The enthalpy change when one mole of a compound in it’s standard state is converted into its free gaseous atoms
Define first ionisation energy
The standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive rage
Define lattice dissociation enthalpy
The standard enthalpy change when one mole of solid ionic compound is broken up into its free gaseous ions
Define standard enthalpy of combustion
The enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions, all reactants and products being in their standard states
