Unit B: Thermochemical Changes Module 3 Flashcards
Thermochemistry
study of energy changes in chemical systems
Kinetic Energy of a System
how fast atoms, ions, molecules are moving
temp measures average kinetic energy of the particles of a system
Potential Energy of a System
energy stored in the bonds btw entities/atoms
Enthalpy (H)
total kinetic and potential energy within a chemical system
Enthalpy Change (delta H)
difference in enthalpy btw the reactants and products
must be at the same temperature and pressure
the sign is constant
Collision-Reaction Theory
collisions occur bc particles are in constant/random motion, if they collide with sufficient energy at the correct orientation a chemical reaction occurs
Activation Energy
minimum amount of energy a particle must have before it can efficiently collide causing a chemical reaction
amount of energy needed/added to a chemical system to initiate a chemical reaction
Bond Energy
energy needed to break a chemical bond or the energy released when a bond is formed
Ep of Endothermic Reactions
products Ep > reactants Ep
Ep of Exothermic Reactions
Products Ep < reactants Ep
Catalysts + points
provide an alternate lower energy pathway w for a reaction (lower activation energy)
- increase the rate of reaction
- aren’t change or used up during chemical process
- they don’t effect enthalpy or bond energy
Molar Enthalpy of Reaction
enthalpy change per 1 mole of a specific substance
