CHEMICAL REACTIONS Part 4 by Jim Alton

1
CHEMICAL REACTIONS Part 4by Jim Alton

• Fri
• Pg 32 to pg 37

2
Sources

• Frank, David Little, John Miller, Steve (2000).
  Science Explorer - Chemical Interactions.
  Needham, MA Upper Saddle River, NJ
• Hurd,, Dean Silver, Myrna Bacher, Angela
  (1993). Physical Science. Needham, MA Englewood
  Cliffs,NJ Prentice Hall.
• Sibert, Gwen (5/16/2004). Types of Equations.
  Retrieved November 23, 2006, from Types of
  Equations Web site http//www.chem.vt.edu/RVGS/AC
  T/notes/Types_of_Equations.html
• Hand (2006). Mr. Hands 8th Grade Science Site,
  Retrieved November 23, 2006, from Mansfield
  Middle School Web Site
• http//www.mansfieldct.org/schools/mms/index.htm
• Quotes by Stephen Wright
• NJCCCS 5.1, 5.6

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Objectives

• Describe the relationship of energy to chemical
  reactions.
• List factors that control the rate of chemical
  reactions.

4
Energy in Chemical Reactions

• Exothermic reaction
• Endothermic reaction

5
Exothermic reaction

• In chemistry, an exothermic reaction is one that
  releases heat (it can be described as "feeling
  hot").

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Endothermic reaction

• In Chemistry an endothermic reaction is one in
  which the reactants have less energy than the
  products, and thus a net input of energy, usually
  in the form of heat, is required.

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Getting Reactions Started

• Activation energy -the threshold energy, or the
  energy that must be overcome in order for a
  chemical reaction to occur.

8
Rates of Chemical Reaction

• The rates can be affected by
• Concentration Increasing the amount of
  reactants makes more particles available to
  react.
• Surface Area Increasing the surface area
  exposes more of the reactant to chemical
  reaction.
• Temperature Increasing temperature makes
  particles move faster and come in contact with
  other particles more often.
• Catalysts Lowers the activation energy.
• Inhibitors Decreases the rate of a reaction.
  (Think about going out on a date. Your Mom is
  driving.)

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