Enthalpy Flashcards
Enthalpy
The heat content that is stored in a chemical reaction
Exothermic
A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants resulting in heat loss to the surroundings.
Endothermic
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants resulting in heat being taken in from the surroundings.
Enthalpy profile
A diagram for a reaction to compare the enthalpy of the reactants with the enthalpy of the products.
Activation energy
The minimum energy required to start a reaction (by the breaking of bonds)
Standard conditions
Pressure 100kpa (1 atm), temperature 298K (25C) and 1.0mol dm^-3 solutions (when solutions are involved)
What is standard state?
The physical state of a substance under the standard conditions
Standard enthalpy of reaction
The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions.
Standard enthalpy of neutralisation
The enthalpy change when one mole of water is formed from reaction between an acid and an alkali, under standard conditions.
Standard enthalpy change of combustion
The enthalpy change when one mole of a substance reacts completely with oxygen under standard conditions.
Standard enthalpy change of formation
The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states.
Specific heat capacity
The energy required to raise the temperature of 1g of a substance by 1C
Bond enthalpy
The enthalpy change that takes place when breaking, by homolytic fission, one mole of a given bond in gaseous molecules.
Average bond enthalpy
The average enthalpy change that takes place when breaking, by homolytic fission, one mole of a given bond in gaseous molecules.
Is bond breaking exothermic or endothermic?
Endothermic
