Energetics Flashcards
exothermic
chemical reactions where heat is given out
endothermic
chemical reactions where heat is taken in
what is the enthalpy change?
the change in energy
what are the units for enthalpy?
kJ/mol
if a reaction is exothermic, the enthalpy value is…
negative: the reaction is GIVING OUT energy
if a reaction is endothermic, the enthalpy value is…
positive: the reaction is TAKING IN energy
catalysts…
lower the activation energy
enthalpy change=
total energy absorbed to break bonds - total energy released in making bonds
bond breaking=
endothermic
bond making=
exothermic
enthalpy (using a calorimeter)=
4.2 x mass of solution x change in temperature (of the water)
energy change per mol=
-heat enthalpy/number of moles of fuel used
number of moles of fuel used=
mass of fuel/Mr
