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Chem Ch 8 pg 244-259


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Calculation of reaction rate
Delta C Ct-Co
Delta T Delta T
Spontaneous processes
processes that take place naturally with no apparent cause of stimulus
processes that give up energy. Energy out.
processes that gain energy. Energy in.
a measurement or indication of the disorder or randomness of a system. The more disorderly a system is, the higher its entropy.
Three ways energy and entropy influence the spontaneity of processes
1. A process will always be spontanious if the energy decreases and the entropy increases
2. when a spontanious process is accompanied by an energy increse, a large entropy increase must also occur.
3. a spontanious process accompanied by an entropy decrease must also be accompanied by a compensating energy decrease.
stable substance:
a substance that does not undergo spontanious changes under the surrounding conditions.
reaction rate:
The speed of a reaction
Reaction Mechanism
the explanation of how a reaction occurs
Reaction Mechanisms are based on the following three assumptions
1. reactant particles must collide with one another in order for a reaction to occur.
2. particles must collide with at least a certain minimum total amount of energy if the collision is to result in a reaction.
3. In some cases, colliding reactants must be orientated in a specific way if a reaction is to occur.
internal energy
The energy associated with vibrations within molecules.
Activation Energy
Energy needed to start some spontanious processes. Once started, the process continues without further stimulus or energy from an outside sorce.
Effective collisions
collisions with the capability to cause a reaction to occur
a substances that changes (usually increases) reaction rates without being used up in the reaction
A substances that decreaes reaction rate.
Homogenious Catalyst
A catalytic substance that is distributed uniformly throughout the reaction mixture.
Heterogenious or surface catalyst
a catalytic substance normally used in the form of a solid with a large surface area on which reactions take place.
state of equilibrium
a condition in a reaction system when the rates of the forward and reverse reactions are equal
Equilibrium Concentrations
the unchanging concentrations of reactants and products in a reaction system that is in a state of equilibrium.
position of equalibrium
an indication of the relative amounts of reactants and products present at equilibrium
Equilibrium expression
An equation relating the equilibrium constant and reactant and product equilibrium concentrations
Equilibrium constant
A numerical relationship between reactant and product concentrations in a reaction at equilibrium
Le Chateliers principle
The position of an equilibrium shifts in responce to changes made in factors of the equilibrium.

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