Enthalpy Flashcards
Definition of enthalpy
The heat energy stored in a chemical system
Definition of enthalpy change
The difference between enthalpy of products and enthalpy of reactants
Definition of exothermic
A reaction in which the enthalpy of the products is SMALLER than the enthalpy of the reactants resulting in heat loss to surroundings. ΔH is negative
Definition of endothermic
A reaction in which the enthalpy of the products is GREATER than the enthalpy of the reactants, resulting in heat being taken from the surroundings. ΔH is positive
Definition of activation energy
The MINIMUM energy required to start a reaction by the breaking of bonds
Enthalpy profile diagram
Shows the enthalpy of reactants and products along with the activation energy and enthalpy change
Standard conditions
Pressure of 100kPa, temperature of 298K and a concentration of 1 moldm-3 for reactions with aqueous solutions
Standard state
The state we find a substance in under standard conditions
Enthalpy change of reaction
The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products in their standard states
Enthalpy change of combustion
The enthalpy change when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in the standard states
Enthalpy change of formation
The enthalpy when one mole of product is formed from its constituent elements under standard conditions
