Science Module

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Science Module

• 8th Grade

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HOT STUFF
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• TAKS Objective 3 The student will demonstrate
  an understanding of the structures and properties
  of matter.
• Complex interactions occur between matter and
  energy.

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TEKS 8.10 (C)

• The student knows that complex interactions occur
  between matter and energy. The student is
  expected to

identify and demonstrate that loss or gain of
heat energy occurs during exothermic and
endothermic chemical reactions.
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Learning Objectives

• identify endothermic and exothermic reactions
  associated with chemical changes
• Explain the loss or gain of heat during chemical
  reactions
• Identify chemical and physical changes associated
  with endothermic and exothermic reactions

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Background

• Heat- transfer of energy

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• Exothermic- heat energy EXITS the system
• - ex. Combustion, evaporation of water
• - surroundings usually feel warmer

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Salt

• An example of an exothermic reaction is the
  mixture of sodium metal and chlorine gas which
  yields table salt.
• 2Na(s) Cl2(g) ? 2NaCl(s) energy

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• Endothermic- heat energy ENTERS the system
• - ex. Cold packs, melting ice
• - surroundings usually feel cooler

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How do cold packs work?

• The outer pouch contains water. The inner pouch
  contains ammonium-nitrate.
• When you pop the inner pouch, the chemical
  reaction absorbs heat energy from the
  surroundings. This is an endothermic reaction.
• The temperature of the solution falls to about 35
  F for 10 to 15 minutes.

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Photosynthesis

• During photosynthesis, plants absorb the energy
  from the sun to convert carbon dioxide and water
  into glucose and oxygen.
• sunlight 6CO2(g) 6H2O(l) ? C6H12O6(aq)
  6O2(g)

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• Physical change- change in size, shape or state
  of matter

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• Chemical Reaction - process in which one or more
  substances are changed into others. Chemical
  reactions are accompanied by a loss or gain of
  energy.

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• True or False
• Chemical reactions always produce heat

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• Chemical reactions can release or
• absorb heat, but can also create
• light, sound or electricity!

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• True or False
• Heat can be lost, destroyed
• or just disappear

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• Heat energy is transferred from one object to
  another, or is transferred to another form of
  energy, but never disappears.
• Law of Conservation of Energy

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• True or False
• Color change is always a physical property

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• Color is a physical property.
• Color change can be the result
• of a chemical change.

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ENGAGE

• Cold Packs
• Rubber Bands
• Glo-sticks

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EXPLORE

• Hot or Not
• students explore endothermic and exothermic
  chemical reactions using baking soda and calcium
  chloride

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EXPLAIN

• List 3 physical properties of matter.
• List 3 physical properties for
• Calcium chloride
• Baking soda
• Phenol red solution

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• Describe what happens with baking soda and
  calcium chloride are mixed.
• Describe what happens with baking soda, calcium
  chloride and phenol red are mixed.
• What are evidences of chemical change?

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• Is this an endothermic or exothermic reaction?
  How do you know?
• Give three examples of exothermic reactions in
  everyday life.

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ELABORATE

• Ice Ice Baby
• Baking soda and vinegar
• Is this endothermic or exothermic? How do you
  know?
• Give 3 examples of everyday endothermic
  reactions.

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• Ice Cream
• Are the changes physical or chemical?
• Is the ice cream endothermic or exothermic? How
  do you know?
• Is the ice/salt mix endothermic or exothermic?
  How do you know?

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EVALUATION

• Complete Type of Change? Endo/Exo chart
• Complete graph analysis questions