enthalpy change Flashcards
define enthalpy change
the heat energy transferred in a reaction at a constant pressure
what is standard enthalpy change measured at?
100kpa and 298k
exothermic reactions
release heat energy into the surroundings
endothermic reactions
absorb energy from the surroundings
formula for enthalpy change
bond breaking (endo)- bond formation(exo)
what are the three different enthalpy changes?
of a reaction
of combustion
of formation
what is enthalpy change of formation?
the enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions
what is the enthalpy of combustion?
when one mole of a substance is completely burned in oxygen understand standard conditions
what is the enthalpy change of a reaction/
the enthalpy change when a reaction occurs in molar quantities shown in a chemical reaction.
what is bond enthalpy|?
energy required to break a bond
define mean bond enthalpy
the average energy need to break a certain type of covalent bond, over a range of compounds
how does the mean bond enthalpy differ from bond enthalpies
because the bond enthalpy doesn’t consider the other compounds the particular bond may exist in
