# Balancing Equations - PowerPoint

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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
 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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