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					Balancing Equations
 Balancing, Writing, and Naming
            Equations
 What is balanced in a chemical
           equation?
Three things
 are balanced
 in a chemical
 equation:
 1. Atoms
 2. Mass
 3. Charge
Balancing Equations
        Balancing Equations
   Law of Conservation
    of Matter:
     In a chemical reaction,
      matter can be neither
      created nor destroyed.
     In a chemical reaction,
      the amount of
      reactants equal the
      amount of products.
    
        Balancing Equations
 Paraphrase:
 Law of Conservation of
  Atoms:
       The number of atoms of
        each type of element
        must be the same on
        each side of the
        equation.
                Counting Atoms
   How many atoms of each element are in the
    following molecules?
    1.   H2SO4
    2.   Ca(OH)2
    3.   NaCl
    4.   (NH3)3P04
    5.   3H2O
    6.   4Al2(CO3)3
            Answers
 1. 2 hydrogen, 1 sulfur, 4 oxygen
 2. 1 calcium, 2 oxygen, 2 hydrogen

 3. 1 sodium, 1 chlorine

 4. 3 nitrogen, 9 hydrogen, 1
  phosphorus, 4 oxygen
 5. 6 hydrogen, 3 oxygen

 6. 8 aluminum, 12 carbon, 36
      Balancing Equations
     Hydrogen     + oxygen         water
            H2   + O2        H2O

   Hydrogen and oxygen are diatomic
    elements.
   Their subscripts cannot be changed.
   The subscripts on water cannot be
    changed.
        Balancing Equation
          H2   + O2           H2O


   Count the atoms on each side.
     Reactant side: 2 atoms H and 2 atoms
      O
     Product side: 2 atoms H and 1 atom O
      Balancing Equations
          H2   + O2          H2O

   If the subscripts cannot be altered,
    how can the atoms be made equal?

   Adjust the number of molecules by
    changing the coefficients.
    Balancing Equations
 Balancing   hints:
   Balance the metals first.
   Balance the ion groups next.

   Balance the other atoms.

   Save the non ion group oxygen and
    hydrogen until the end.
      Is this equation balanced?
     NaCl + H2O  NaOH + Cl2
   left side has 1Na, 1Cl, 2H, and 1O
   right side has 1Na, 1O, 1H, and 2Cl
 NO!!!!!!    It is not balanced!!
      Is this equation balanced?
    HCl + NaOH NaCl+ H2O
   left side has 2H, 1Cl, 1Na, and 1O
   right side has 1Na, 1Cl, 2H, and 1O
 Yes!!!!!!   It is balanced!!
      Is this equation balanced?
    Ca + H2O Ca(OH)2 + H2
   left side has 1Ca, 2H, 1O
   right side has 1Ca, 2O, 4H
   No!!!!!! It is not balanced!!


   How can we make it balance????
    Balancing Equations
      H2   + O2          2H2O
 Reactants: 2 atoms of H and 2 atoms
  of O
 Products: 4 atoms of H and 2 atoms
  of O
 H is no longer balanced!
      Balancing Equations

          2H2   + O2        2H2O

   Reactant side: 4 atoms of H and 2 atoms
    of O
   Product side: 4 atoms of H and 2 atoms
    of O
   It’s Balanced!
        Balancing Equations
              N2   + H2          NH3
           Nitrogen + hydrogen   ammonia


   Count atoms.
     Reactants: 2 atoms N and 2 atoms H
     Products: 1 atom N and 3 atoms of NH3
    Balancing Equations
 Nothing is balanced.
 Balance the nitrogen first by placing a
  coefficient of 2 in front of the NH3.


        N2   + H2        2NH3
    Balancing Equations
 Hydrogen is not balanced.
 Place a 3 in front of H2.

 Reactant side: 2 atoms N, 6 atoms H

 Product side: 2 atoms N, 6 atoms H



       N2   + 3H2       2NH3
    Balancing Equations
        Ca3(PO4)2 + H2SO4
          CaSO4 + H3PO4

 Count atoms.
 Reactants: Ca – 3 atoms, P – 2
  atoms, O – 8 atoms; H – atoms, S – 1
  atom, O – 4 atoms
    Balancing Equations
 Side   note on Ca3(PO4)2

 The subscript after the phosphate
  indicates two phosphate groups.
 This means two PO43- groups with
  two P and eight O atoms.
      Balancing Equations
         Ca3(PO4)2      + H2SO4
            CaSO4 + H3PO4

   Count atoms in the product.
   Ca atoms – 1, S atom – 1, O atoms – 4; H
    atoms – 3, P atom – 1, O atoms - 4
       Balancing Equations
   In this equation, the ion groups do not
    break up.
   Instead of counting individual atoms, ion
    groups may be counted.

         Ca3(PO4)2 + H2SO4
             CaSO4 + H3PO4
         Balancing Equations
         Ca3(PO4)2 + H2SO4
             CaSO4 + H3PO4

   Reactants: Ca2+ – 3, PO43- - 2, H+ – 2,
    SO42+ - 1
   Products: Ca2+ - 1, SO42- - 1, H+ - 3, PO43-
    -1
      Balancing Equations
   Balance the metal first by placing a
    coefficient of 3 in front of CaSO4.
   Products: Ca – 3 atoms, SO42- - 3 groups


         Ca3(PO4)2+ H2SO4
           3CaSO4 + H3PO4
       Balancing Equations
   Three sulfate groups are needed on the
    reactant side so place a coefficient of 3 in
    front of H2SO4.
   3H2SO4 gives 6 H+ and 3 SO42-.
   Neither phosphate nor calcium is
    balanced.
        Ca3(PO4)2 + 3H2SO4
            3CaSO4 + H3PO4
      Balancing Equations
   A coefficient of 2 placed in front of
    H3PO4 which balances both hydrogen
    and phosphate.


        Ca3(PO4)2+ 3H2SO4
          3CaSO4 + 2H3PO4
       Balancing Equations
                   Cu + H2SO4
             CuSO4 + H2O + SO2

   The sulfate group breaks up. Each atom
    must be counted individually. Ugh!
   Reactants: Cu – 1, H – 2, S – 1, O – 4
   Products: Cu – 1, S – 1, O - 4, H – 2, O –
    1, S – 1, O - 2
    Balancing Equations
 Sulfur is not balanced.
 Place a two in front of sulfuric acid.

 Count atoms: 2 H2SO4 H – 4, S – 2,
  O-8

            Cu + 2H2SO4
            

        CuSO4 + H2O + SO2
    Balancing Equations
 Hydrogen needs to be balanced so
  place a 2 in front of the H2O.
 Count the number of atoms.


           Cu + 2H2SO4
       CuSO4 + 2H2O + SO2
       Balancing Equations
   Reactants: Cu – 1, H – 4, S – 2, O – 8
   Products: Cu – 1, S – 1, O – 4, H – 4, O –
    2, S – 1, O – 2 = Cu – 1, S – 2, H – 4, O
    –8
                  It’s balanced!


               Cu + 2H2SO4
               

          CuSO4 + 2H2O + SO2
    Balancing Equations
 This method of
  balancing
  equations is the
  inspection
  method.
 The method is
  trial and error.
 Practice.
       Writing and Naming
             Nickel + hydrochloric acid
         Nickel(II) chloride + hydrogen


   Write the corresponding formula
    equation and then balance the
    equation.
       Writing and Naming
   Write each formula independently.
   Ignore the rest of the equation.
   Balance the equation after writing the
    formulas.

           Ni + HCl       NiCl2 + H2
           Ni + 2HCl       NiCl2 + H2
       Writing and Naming
   Remember the diatomic elements: H2, N2,
    O2, F2, Cl2, Br2, and I2.
    Writing and Naming
            Cu + H2SO4
        CuSO4 + H2O + SO2




 Balance the formula equation.
 Write the word equation.
       Writing and Naming
               Cu + 2H2SO4
               

          CuSO4 + 2H2O + SO2


   Write the names:
   Cu by itself is just copper. Copper(I) or
    copper(II) would be incorrect.
   H2SO4 should be named as an acid.
   Sulfuric acid
       Writing and Naming
   CuSO4 has a SO42- group so Cu must
    be 2+. Some metals must have
    Roman Numerals. Copper(II)
    sulfate
 H2O is known as water.
 SO2 is a nonmetal compound. Its
  name is either sulfur dioxide or
  sulfur(IV) oxide.
   Writing and Naming
          Cu + 2H2SO4
      CuSO4 + 2H2O + SO2




     Copper + sulfuric acid 
 Copper(II) sulfate + water + sulfur
                dioxide
    Balancing Equations

 Chapter  8
 Practice!

 Practice!

 Practice!

				
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