Rates and Equilibrium Flashcards
Activation energy
The minimum energy required to start a chemical reaction.
Activated complex
A high energy, unstable, temporary transition state between the reactants and products.
A catalyst
A substance that increases the rate of chemical reaction but remains unchanged at the end of the reaction.
The reaction rate of a chemical reaction
The change in concentration per unit time of either a reactant or product.
Heat of Reaction
The net change in chemical potential energy of the system. ΔH > 0 for endothermic reactions and ΔH < 0 for exothermic reactions.
Exothermic reactions
Reactions which transform chemical potential energy into thermal energy.
Endothermic reactions
Reactions which transform thermal energy into chemical potential energy.
Equilibrium constant
An expression of the concentration of products (gases and solutions only) over the concentration of reactants (gases and solutions only) for a reaction that is in equilibrium.
Dynamic equilibrium
Reversible reaction in which the forward and reverse reactions are taking place at the same rate hence the concentrations of products and reactants are constant.
Closed system
One in which mass is conserved inside the system but energy can enter or leave the system freely.
Open system
One in which both energy and mass can be exchanged between the system and its surroundings
Reversible reaction
A reaction in which products can be converted back into products.
Le Chatelier’s Principle
When an external stress (change in pressure, temperature or concentration) is applied to a system in dynamic chemical equilibrium, the equilibrium point will change in such a way to counteract that stress.
Yield
A measure of the extent of a reaction, generally measured by comparing the amount of product formed to the amount of possible product.
