chemical reactions can occur only when reacting particles collide with each other and with sufficientenergy
activation energy
minimum amount of energy that particles must have to react
Catalysts
change the rate of chemical reactions but are not used up
increase the rate of reaction by proving a differentpathways for the reaction that has a loweractivationenergy
Different reactions need different catalyst
Reversible reactions
products of the reaction can react to produce the original reactants:
-A + B ↔C+D
direction of reversibl reaction a can be changed by changing conditions:
-Ammonium chloride ↔ammonia + hydrogen chloride
(forward reaction heat)
(Reverse reaction cool)
reversible reactions (Endo / EXO)
hydrated copper sulfate (blue) ↔anhydrous copper sulfate + water (white)
(Forward reaction is endo)
(Reverse reaction is exo)
if a reversible reaction is exothermic in one direction and endothermic in the opposite direction, the same amount of energy is transferred in each case