Reaction Rates

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Chapter 19

• Reaction Rates
• And
• Equilibrium

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Rates

• Measures the speed of change over an interval of
  time

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Collision Theory

• Atoms, ions, and molecules can react to form
  products when they collide with enough kinetic
  energy.

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Activation Energy

• The minimum amount of energy that particles must
  have to react.

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Transition State

• The point at the peak of the activation energy
  where compounds change back to reactants or form
  new products.

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4 Factors affecting Reaction Rates

• 1.Temperature Increase in temperature increase
  in KE, w/more KE one has more and harder
  collisions causing more product to form

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2. Concentration

• More molecules means greater chance of collision
  resulting in the formation of new products.

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3. Particle Size(increased surface area)

• The more surface area you have the greater the
  chance of collision.

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4. Catalyst

• A substance that speeds up a reaction without
  being used up in that reaction.
• Usually written above the yields sign in an
  equation.

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Inhibitors

• Works against the catalyst.

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Reversible Reactions

• The reaction occurs in both directions at the
  same time.

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2 SO2 O2 2 SO3
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Chemical Equilibrium

• A state at which the forward and reverse reaction
  occur at the same rate.

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DOES NOT MEAN

• Same amount of product and reactant formed.

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LeChatliers Principle

• If stress is applied to a system in dynamic
  equilibrium, the system changes to relieve the
  stress.

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Concentration

• Increasing the concentration will always change
  the equilibrium away from the increased
  concentration.

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H2CO3 CO2 H2O
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Temperature

• Equilibrium shifts in the direction that absorbs
  the heat

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2 SO2 O2 2 SO3 Heat
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Pressure (in gasses)

• Only affects equilibrium if there is an unequal
  of moles. Equilibrium moves to the side w/less
  moles.

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K(eq) Equilibrium Constant

• The lower case letters of moles of that
  compound
• aA bB cC dD

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K(eq)
Cc x Dd
Aa x Bb
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K(eq) Equilibrium Constant

• It shows whether products or reactants are
  favored in the reaction.
• K(eq) gt 1 Products are favored
• K(eq) lt 1 Reactants are favored