Word Equations

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Word Equations Types of Reactions

• CHEM

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Chemical equations can also be written in words

• Chemical names are used
• Reactants on the left of arrow
• Products on the right

Hydrogen oxygen ? water 2H2 O2 ? 2H2O
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Write a word equation

• Write a word equation for the reaction below
• Iron reacts with oxygen to produce iron (III)
  oxide (rust)

iron oxygen ? iron (III) oxide
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Types of reactions

• Several ways to categorize reactions
• Synthesis (Combination)
• Decomposition
• Single Replacement
• Double replacement
• Combustion

How do you know which type of reaction is
occurring?
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Look at the Reactants products!

• Check to see if the of substances is
  increasing or decreasing.
• Look to see if elements are switching places.

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Synthesis Reactions (Combination)
Two or more simple substances combine to form a
more complex substance. Two or more reactants
yielding one product reactant reactant
-------gt product For example, simple hydrogen
gas combined with simple oxygen gas can produce a
more complex substance-----water!The chemical
equation for this synthesis reaction looks like
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Synthesis Cartoon

• In the cartoon, the skinny bird (reactant) and
  the worm (reactant) combine to make one product,
  a fat bird

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Decomposition Reactions
Complex substance breaks down into its more
simple parts. One reactant yields 2 or more
products. reactant -------gt product
product For example, water can be broken down
into hydrogen gas and oxygen gas. The chemical
equation for this decomposition reaction looks
like
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Decomposition Cartoon

• In this cartoon the egg (the reactant), which
  contained the turtle at one time, now has opened
  and the turtle (product) and egg shell (product)
  are now two separate substances.

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Single-Replacement Reactions

• Notice, the guy in the orange shirt steals the
  date of the other guy. So, a part of one of the
  reactants trades places and is in a different
  place among the products.

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Single-Replacement Reactions

• Single uncombined element replaces another in a
  compound.
• Two reactants yield two products.
• reactant reactant ---------gt product product
• For example when zinc combines with hydrochloric
  acid, the zinc replaces hydrogen. The chemical
  equation for this single replacement reaction
  looks like

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Double-Replacement Reactions

• Parts of two compounds switch places to form two
  new compounds.
• Two reactants yield two products.
• reactant reactant ---------gt product product
  
• For example when silver nitrate combines with
  sodium chloride, two new compounds--silver
  chloride and sodium nitrate are formed because
  the sodium and silver switched places.

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Double-Replacement Cartoon
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Combustion Reactions

• Element or compound reacts with oxygen
• -usually produces energy as heat light
• -commonly involve hydrocarbons
• C6H8 8O2 ? 6CO2 4H2O