5. Chemical Energetics Flashcards
Endothermic Reactions
A reaction that takes in energy from the surroundings, usually as heat.
Bonds are broken (requires energy)
Exothermic Reaction
A reaction that gives out energy to the surroundings, usually as heat.
Bonds are made out (gives out energy)
Reaction pathway diagrams
Graphical method for showing the changes in energy levels during a chemical reaction.
Activation Energy
The minimum energy required for a reaction to happen.
(Minimum amount of energy particles need to be able to collide with each other instead of just bouncing off each other)
Enthalpy Change
The difference in energy between reactants and products. Units in kJ/mol with symbol ΔH .
Bond energy
The amount of energy in kJ/mol that is needed to break one mole of a bond.
Enthalpy change (formula)
ΔH = energy of the reactants – energy of the products
ΔH = bonds broken – bonds formed
Reaction Pathway Diagrams (exothermic reactions)
The reactants begin with a higher energy level than the products.
Reaction Pathway Diagrams (endothermic reactions)
The reactants begin with a lower energy level than the products.
Exothermic reactions (Enthalpy Change)
-ΔH
Endothermic reactions (Enthalpy Change)
+ ΔH
Bond Breaking (What type of reaction)
Endothermic
Bond Making (What type of reaction)
Exothermic
Activation Energy (symbol)
Ea
