Chemical Equation

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Chemical Equation Reaction Notes

• Chemical reactions occur when chemical bonds
  (ionic, covalent) between atoms are broken and
  new bonds are formed
• Chemical equation used to describe chemical
  reactions through symbols numbers

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Example of chemical equationaluminum sulfate
plus barium chloride yields aluminum chloride
plus barium sulfate

• Al2(SO4)3 3 BaCl2 ? 2 AlCl3 3
  BaSO4
• Label the following
• Reactants - Products -Coefficients
• - Subscripts - Produces or yields

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Terms or symbols used in equations

• or and - used as divider between
  reactants or products
• ? yields, reacts, produces, forms,
• reversible reaction
• CATALYST is something that speeds up the
  reaction, but it is not used as a chemical part
  of the reaction written on top of the yield sign
• Heat or ? or MnO2 or
  elec

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More terms and symbols

• (s) solid
• (l) liquid
• (aq) aqueous, dissolved in water
• (g) gas
• NR no reaction

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• There are 5 types of chemical reactions

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1 - Synthesis

• Reactants combine to form 1 compound
• (aka, combination rxn)
• reactant reactant ?
  product
• Basically A B ? AB
• Ex 2 H2 O2 ? 2 H2O
• Ex C O2 ? CO2

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Synthesis Reaction (continued)

• Here is another example of a synthesis rxn

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2 - Decomposition

• occur when a compound breaks up into 2 or more
  products (can be elements or compounds)
• 1 Reactant ? Product Product
• In general AB ? A B
• Ex 2 H2O ? 2 H2
  O2
• Ex 2 HgO ? 2 Hg
  O2

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Decomposition (continued)

• Another view of a decomposition reaction

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3 - Single Replacement

• occur when one element replaces another in a
  compound (aka, single displacement)
• AB C ? CB
  A
• Metals must be more reactive in order to replace
  another metal (called the Activity Series)
• Zn(s) HCl(aq) ? ZnCl2 H2(g)

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4 Double Replacement

• Occurs when 2 ionic compounds switch partners
  and produce 2 different compounds
• Compound compound ? compound compound
• AB CD ? AD CB
• Ex AgNO3(aq) NaCl(s) ? AgCl(s)
  NaNO3(aq)

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5 - Combustion

• occur when a hydrocarbon reacts with oxygen
• This is also called burning
• In general CxHy O2 ?
  CO2 H2O
• Products in combustion are ALWAYS carbon dioxide
  and water. (incomplete combustion will also
  produce carbon monoxide)