Energetics - Chapter 4 Flashcards
What is an exothermic reaction
A reaction that gives out energy from the surrondings
What is an endothermic reaction
A reaction which takes energy in from the surrondings
What type of reaction is breaking bonds
Endothermic
What type of reaction is forming bonds
Exothermic
What is energetics
It is the study of heat changes during chemical reactions
What is temperature
It is a measure of the average kinetic energy of the particles in a system
What is heat
It is a measure of the total energy of all particles present in a given amount of a substance
Measured in KJ/mol
What is an enthalpy change
It is when we measure a heat change at constant pressure
What is a standard enthalpy change
It is the heat change measured under standard conditions ( 100,000Pa and a stated temperature) with all reactants and products in their standard states
What is standard enthalpy of combustion
This is the enthalpy change when one mole of an element or compound is completely burned in oxygen under standard conditions with all reactants and products in their standard states
What is standard enthalpy of formation
This is the enthalpy change when one mole of a compound is formed from its elements under standard conditions with all reactants and products in their standard states
What is the enthalpy of formation for any element
0
What is the equation for the heat energy change
q = M x C x Change in Temp
What technique is used to measure enthalpy change
Calorimetry
What is the first law of thermodynamics
Energy cannot be created or destroyed, only converted from one form to another
What is Hess’s Law
The enthalpy change at constant pressure in a reaction is independent of the route / path taken (and depends only on the initial and final states)
What is the equation for enthalpy change
Total enthalpy’s of formation of products – Total enthalpy’s of formation of reactants
This can also be used for combustion data
What is the bond dissociation enthalpy
The enthalpy required to break a particular covalent bond in a molecule when all species are in a gaseous state
What is the mean bond enthalpy
It is the average value of the bond dissociation enthalpy of a particular type of bond in a range of different compounds
