Topic 5 - Energetics / Thermochemistry Flashcards
Average bond enthalpy
The average enthalpy change of breaking one mole of a bond in a gaseous atom into its constituent gaseous atoms.
Electron affinity
Enthalpy change when an electron is added to an isolated atom in the gaseous state
Endothermic
A reaction in which energy is absorbed. ΔH is +.
Reactants more stable than products.
Enthalpy
The internal energy stored in the reactants.
Only changes in enthalpy can be measured.
Exothermic
A reaction in which energy is evolved. ΔH is –.
Products more stable than reactants
Hess’ law
Enthalpy change = diffrence between enthalpy of products and enthalpy of reactants. It is independent of pathway.
Spontaneous
A reaction that has a natural tendency to occur.
Standard conditions
298 K (c+273) and 1 atm.
Temperature
A measure of the average kinetic energy.
Bond dissociation enthalpy
The energy change when one mole of a specific bond is broken or created under standard conditions.
Enthalpy of Combustion
The energy released when one mole of a compound is burned in excess oxygen.
Standard enthalpy of formation
The energy change when one mole of a compound is formed under standard conditions from its constituent elements in their standard states.
Standard enthalpy of solution
The energy change when one mole of a substance is dissolved in an infinite amount of water under standard conditions.
