enthalpy change Flashcards
define enthalpy change
the heat energy change per mole at a constant pressure
what are the standard conditions for enthalpy change
298K and 100kPa
define enthalpy change of formation
the enthalpy change when one mole of a substance is formed from it’s constituent elements in their standard states
define enthalpy change of combustion
the enthalpy change when one mole of substance is completely burnt in oxygen
naturally what does the element sulfur exist as
S8
naturally what does the element phosphorus exist as
P4
list the names of the diatomic molecules
halogens
hydrogen
nitrogen
oxygen
(X2)
what elements naturally exist as a liquid
Hg
Br2
define mean bond enthalpy
energy required to break one mole of a covalent bond (to make gaseous atoms) averaged across lots of compounds
what is the equation for enthalpy change from enthalpy data
bond enthalpy of reactants - bond enthalpy of products
define bond dissociation energy
the enthalpy change required to break a covalent bond with all species in a gaseous state
