Chemical Reaction Types

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Chemical Reaction Types

• Science 10

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Reaction Types

• There are different types of reactions that occur
  in science
• To figure out the type of reaction you are
  dealing with, you need to consider the reactants
  (on the left of the arrow) and the products (on
  the right of the arrow)

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Exothermic and Endothermic

• During all chemical reactions, energy is either
  absorbed or released, in the form of heat, light,
  electricity, or sound
• Exothermic reactions energy is released. Ex.
  Burning fuel
• Endothermic reactions energy is absorbed. Ex.
  Cold packs

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• Physical changes can be exothermic or endothermic
• Ex. Vaporization of water is endothermic
• Ex. Condensation of water is exothermic

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Law of Conservation of Energy

• Energy can be converted from one form to another,
  but the total quantity of energy is the same
• Energy is required to break bonds, so products of
  an exothermic reaction have less energy in their
  bonds than the reactants
• Energy is required when bonds form, therefore
  products of an endothermic reaction have more
  energy in their bonds than the reactants

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1) Synthesis

• 2 reactants form 1 new single product
• 2Mg(s) O2(g) ? 2MgO(s) thermal energy
• This is exothermic

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2) Decomposition

• 1 reactant breaks apart to form 2 products
• H2O(l) ? H2(g) O2(g)

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3) Combustion

• Always a hydrocarbon (made from C and H) mixing
  with oxygen to make carbon dioxide and water
• CH4 O2 ? CO2 H2O

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4) Single Displacement

• Element Compound New element New Compound
• Switching the metal most times
• Zn(s) HCl(aq) ? ZnCl2(aq) H2(g)

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• Fe(s) Cu(NO3)2(aq) ? Cu(s) Fe(NO3)2(aq)
• Metals differ in their reactivity
• A more reactive metal will displace a less
  reactive metal in a reaction
• Cu(s) Fe(NO3)2(aq) ? no reaction
• Since copper is less reactive (lower on the
  activity series) than iron, no displacement will
  occur

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5)Double Replacement Reactions

• 2 compounds give 2 new compounds
• The metals switch places
• Example
• AgNO3(aq) NaCl(aq) ? AgCl(s)
  NaNO3(aq)

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• Also known as a neutralization reaction
• A solid formed when two solutions mix is called a
  precipitate
• You can tell a double displacement reaction has
  occurred if either a precipitate or water forms
  as one of the products

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Identify the "type" for each reaction below, and
balance

• Ca O2 ? CaO
• Br LiI ? LiBr I2
• Al FeBr2 ? AlBr3 Fe
• MgO HCl ? MgCl2 H2O
• C4H10 O2 ? CO2 H2O
• Zn AgCl ? ZnCl2 Ag
• CuBr KCl ? KBr CuCl