Energetics Flashcards
what is enthalpy chnsge and what is its units
the change of heat at a constant pressure
Kj mol-1
what is enthaply chgabge for exothermic reactions
always negative
what is enthaply chgabge for endothermic reactions
positive
what is the definition of standard enthaply change
refers to reactions done under standard conditions and all substances in their standard states
what are the standard conditions
298K
100KPa
what is the standard enthalpy of combustion
the enthalpy change when 1 mol of a substance is completely burned in oxygen under standard conditions and all substances present in their standard states
are enthalpy of combustion alwyas endo or exo
exo
what is the standard enthaply of formation
the enthaply change when 1 mol of a substance is formed from its elements under standard conditions and all substances in their standard states
what is the enthaply of formation of an element
zero by definition
what is the definition of hess law
enthaply change is independent of the route taken
what is the equation when using enthalpy of combustion data
sum of all REACTANTS - SUM of all PRODUCTS
crap
what’s calorimetry
a technique used to find how much heat energy is released or absorbed
this then can be used to find enthalpy change
what are the 2 equations for calorimetry
q = m x c x change in temp
🔺H = q/1000
————-
moles
what’s bond disassociation energy
enthalpy change to break the bond in 1 mole of gaseous molecules to form gaseous atoms
definition of mean bond enthalpy
enthalpy required to break 1 mol of
covalent bonds averaged over a range of compounds
