9. ENTHALPY Flashcards
What is enthalpy?
A measure of the heat energy in a chemical system
Draw an Exothermic reaction profile
y-axis = enthalpy, H
x-axis = progress of reaction
products lower than reactants
Draw an Endothermic reaction profile
y-axis = enthalpy, H
x-axis = progress of reaction
products higher than reactants
Define Activation energy
The minimum energy required for a reaction to take place
What are the standard conditions?
- pressure = 100kPa
- temperature = 298K
- concentration = 1moldm^-3
- standard states
Define standard enthalpy change of reaction
The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states
Define standard enthalpy change of formation
The enthalpy change that takes place when one mole of a compound 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 that takes place when one mole of a substance reacts completely with oxygen under standard conditions, with all reactants and products in their standard states
Define enthalpy change of neutralisation
The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H20(l), under standard conditions, with all reactants and products in their standard states
