Enthalpy Changes Flashcards
Define enthalpy.
A measure of heat energy in a chemical system
Define enthalpy change.
The difference in enthalpies of reactants and products
What is the formula for delta H.
Change in products - change in reactants
What is the conservation of energy?
Energy can not be created or destroyed, only transferred between the system and surroundings
What is an exothermic reaction?
Heat energy is transferred from the system to the surroundings, this means delta H is negative
What is an endothermic reaction?
Heat energy is transferred from the sorroundings to the system, this means delta H is positive
Draw the enthalpy diagram for endothermic/exothermic reaction
What is the activation energy
The minimum amount of energy required for a reaction to take place
What are the standard conditions of a reaction
- 101KPA
- 298K
- 1 mol dm-3
Define the standard enthalpy change of a reaction
The enthalpy change that accompanies a reaction in the molar quantities as displayed in a chemical equation, with all products and reactants in standard states and under standard conditions
Define standard enthalpy change of formation
The enthalpy change that occurs when one mole of a substance is formed from its elements under standard conditions with all reactants and products in their standard states
Define standard enthalpy change of combustion
The enthalpy change of a reaction when one mole of a substance is burned completely with oxygen under standard conditions and with all products and reactants in their standard states
Define standard enthalpy change of neutralisation
The enthalpy change of a reaction that accompanies a reaction of an acid with base to form one mole of water under standard conditions with all products and reactants in their standard states
