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Section 2.4 . Chemical Reactions. Chemical reactions change substances into different substances by breaking and forming bonds. Chemical reactions are responsible for all the actions of organisms. Examples Photosynthesis Respiration (breathing) Digestion.
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Section 2.4 Chemical Reactions
Chemical reactions change substances into different substances by breaking and forming bonds.
Chemical reactions are responsible for all the actions of organisms. • Examples • Photosynthesis • Respiration (breathing) • Digestion
Reactants are changed in a reaction • EXAMPLE: • Products are formed in a reaction • Oxygen+Sugars CO2 + Water (Reactants)(Products)
Two Types of Reactions Exothermic Endothermic • Energy EXITS! • The prefix “exo-” means “out” • Example: • respiration • Energy goes IN! • The prefix “Endo” means “into” • Example: • - photosynthesis
Vocabulary Check • Making and breaking chemical bonds are examples of ____________. • Bonds are broken in the ______, which are the chemicals that are changed during the process. • Bonds are made in the ________, which are the chemicals that result from the process.
Vocabulary Check cont… • The ________ is the amount of energy needed to start a reaction. • If a reaction absorbs more energy than it releases, it is called an __________ reaction. • If a reaction releases more energy than it absorbs, it is called an __________ reaction.
Endo or Exo? 1.
Reactants and Products? 3. 2H2O2 2H2O + O2