Chemistry Chapter 16: Reaction Rates

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Chemistry Chapter 16 Reaction Rates

• The reaction rate, of a reaction, is the ? of
  reactants or products per second.
• The ? of reactants ? of products, much like the
  ? of amount of sand in the top of an hour-glass
  changes to the ? of change in the bottom.
• Reaction Rate ? of reactants
• second
• Units of reaction rate are M/s(mol/L)1/smol/L
  s

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Collision Theory

• Collision Theory states that there must be
  collisions to cause reactionsthe more number and
  greater force of collisions, the more reactions.
• Once reacting particles collide, they form the
  activated complex, which is a morph of the
  reactant and product.
• Reactions require activation energy in order for
  a reaction to start.

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Energy Diagrams

• An energy diagram graphs energy (y) v time (x)
• An activation energy (?E) is required to start
  the reation.
• Multiple humps indicate multiple steps called
  elementary reactions.
• A transition state or activated complex exists
  during activation.
• The taller the front slope, the slower the
  reaction, the shorter, the faster.
• Intermediates are products formed by elementary
  reactions, that may or may not stay in tact for
  the overall reactiionthey may be used up by the
  next step.

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Spontaneity and Reaction Rate

• ?G is Gibbs free energy.
• - ?G means a spontaneous reaction, ?G means
  non-spontaneous.

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16-2 Factors Affecting Reaction Rate

1. The nature of reactants.
2. Concentration
3. Larger surface area/smaller particle size.
4. Temperature.
5. Catalysts.
6. Inhibitors.

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Catalysts

• Catalysts work by lowering the required
  activation energy.

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Types of Catalysts

• Homogeneous catalysts are the same physical state
  as the reactants.
• Heterogeneous catalysts are a different physical
  state as the reactants.