Equilibrium & Reaction Rates(P.137-141) 7%

Front 1

Reaction Rate

Back 1

-is a measure of the change in the concentration of reactants or products over time in a chemical reaction.

-Factors that influence Reaction Rate:
1.) Concentration of the reactants
2.) Temperature
3.) Presence of a catalyst
4.) Physical state of the reactants

Front 2

Activation Energy [E(a)]

Back 2

-is defined as the minimum energy needed to initiate a chemical reaction, and it is symbolized by E(a).

Front 3

Chemical Equilibrium (K or K(eq))

Back 3

-has been reached in a reaction when the rate of the forward reaction is equal to the rate of the reverse reaction.

Front 4

Equilibrium Constant Expression Rules

Back 4

1.) Pure solids do not appear in the equilibrium expression.
2.) Pure liquids do not appear in the equilibrium expression.
3.) Water, either as a liquid or solid, does not appear in the equilibrium expression.
4.) When a reactant or product is preceded by a coefficient, its concentration is raised to the power of that coefficient in the K(eq) expression.
5.) When the K(eq) of a reaction has been multiplied by a number, the K is raised to the power of the multiplication factor (K(n)), so if it has been multiplied by 2, K is squared, if it has been multiplied by 3, K is cubed, and so on.
6.) The K(eq) of a reaction occurring in the reverse direction is simply the inverse of the K(eq) of the reaction occurring in the forward direction (1/K(eq)).
7.) The K(eq) of of a net reaction that has two or more steps is found by the product of the K(eq)s for each of the steps: K(s)=(K1xK2xK3...).

Front 5

Le Chatelier's Principle

Back 5

-basically states that if stress is applied to a system at equilibrium, the position of the equilibrium will shift in the direction that reduces the stress to reinstate equilibrium.
-For example, if more reactants are added to the system, the reaction will shift in the forward direction, and if more products are added, the reaction will shift in the reverse direction.
-If heat is added to the system and the reaction is exothermic, heat should be thought of as a product and the reaction will shift to the left; if the reaction is endothermic and heat is added, the reaction will shift to the right. The addition of pressure will cause a shift in the direction that results in the fewer number of moles of a has, while if pressure is relieved, the reaction will shift in the direction that produces more moles of a gas.