CONCURRENT ENROLLMENT

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CHAPTER 5

• CONCURRENT ENROLLMENT

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CHEMICAL EQUATIONS

• Reactants
• Substances that are undergoing a chemical change
• Left side of the arrow in a reaction
• Products
• Substances that are formed after a chemical
  change
• Right side of the arrow in a reaction
• Law of conservation of matter
• Atoms cannot be created nor destroyed in chemical
  reactions
• Balanced equation
• An equation in which the number of atoms of each
  element in the reactants is the same as the
  number of atoms of that same element in the
  products

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OXIDATION-REDUCTION REACTIONS

• An oxidation-reduction reaction involves transfer
  of electrons
• Addition of O2 or H2
• Species that lose electrons
• Oxidized or oxidation
• Species that gain electrons
• Reduced or reduction
• Oxidizing agent
• What causes oxidation
• Reducing agent
• What causes reduction

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TYPES OF REACTIONS

• DECOMPOSITION
• A single reactant is broken down
• SINGLE REPLACEMENT
• One element replaces another
• DOUBLE REPLACEMENT
• Atoms or ions exchange partners

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CONTINUED

• COMBUSTION
• Hydrocarbons with oxygen making carbon dioxide
  and water
• COMBINATION OR COMPOSITION
• Formation of a single product

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REDOX

• The concept of oxidation numbers explain
  oxidation and reduction
• Oxidation increases the oxidation number (loss
  electrons)
• Reduction decreases the oxidation number (gains
  electrons)

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CONTINUED

• Balancing redox equations
• Half-equation method
• Split the equation into two half reactions
• One for reduction and the other for oxidation
• Balance one of the half-reactions with respect to
  both atoms and charge , use water to add
  oxygens, add hydrogen ions (in an acidic
  solution you will have both), add electrons to
  balance charge
• Balance the half-reactions
• Combine the two in such away as to eliminate all
  the electrons

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ENERGY AND REACTION

• EXOTHERMIC REACTIONS
• When a reaction releases heat as part of the
  product
• ENDOTHERMIC REACTIONS
• When a reaction absorbs heat so that the reaction
  will occur. Heat is one of the reactants

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THREE STEPS IN BALANCING

• Determine the type of reaction. What are the
  reactants, products and physical states involved
• Write a unbalanced equation
• Balance equation, start with the most complicated
  molecule. Find the right coefficient to give the
  same number of each type of atom of both sides.
  DO NOT CHANGE THE IDENTITIES

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MOLE TO MOLE

• Reactions involving masses in grams of reactants
  and products can be achieved by converting grams
  into moles

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LIMITING REACTANTS AND THEORETICAL YIELD

• When a reaction goes to completion and there is
  no loss of product, then the amount produced is
  called the theoretical yield
• Many times there is one reactant that is
  expensive so an excess of the other reactant is
  used, this ensures that all the expensive
  reactant is used. When the limiting reactant is
  used up the reaction stops.
• Method to determine limiting reactant
• Calculate the amount of product that would be
  formed if the first reactant was consumed
• Repeat step 1 for second reactant

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EXPERIMENTAL YIELD

• Experimental yield yield
• yield actual (experimental) yield X 100
• theoretical yield