5&15. Energetics Flashcards
Temperature =
a measure of the average kinetic energy of the particles in a substance.
Specific heat capacity =
the energy required to raise the temperature of 1kg of a substance by 1K.
Enthalpy change =
the amount of heat evolved or absorbed in a reaction carried out at constant pressure (kJmol-1).
Exothermic reaction =
a chemical reaction that releases energy because the energy released forming bonds is greater than the energy required to break the bonds. ΔH<0
Endothermic reaction =
a chemical reaction that absorbs energy because the energy released forming bonds is less than the energy required to break the bonds. ΔH>0
Enthalpy change of formation (ΔHf) =
the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states, and at a pressure of 1 bar (100 kPa).
Enthalpy change of combustion (ΔHc) = .
the enthalpy change when 1 mole of a compound is completely burnt in oxygen gas at 298K and 1 bar pressure
Standard enthalpy of reaction (ΔHr⊖) =
the enthalpy change that occurs in a system when matter is transformed by a chemical reaction under standard conditions.
Hess’s law =
the enthalpy change for a reaction that is carried out in a series of steps is equal to the sum of the enthalpy changes for the individual steps.
Average bond enthalpy =
the energy required to break one mol of a bond in a gaseous molecule averaged over similar compounds.
Bond dissociation energy =
the energy required to break one mole of specific bonds in a specific molecule in the gaseous state.
Enthalpy of hydration =
the enthalpy change when 1 mole of gaseous ions dissolves in sufficient water to give an infinitely dilute solution.
First ionisation energy =
the energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+.
Enthalpy of atomization =
the enthalpy change that accompanies the total separation of all atoms in one mol of a chemical substance.
Electron affinity =
the energy change when an electron is added to each of the neutral atoms or molecules in one mol of the substance in the gaseous state to form a negative ion.
