Part 3: Balancing Equations (text pages 280-283)

����Does “H2 + O2 →→→→ H2O” obey the Law of Conservation of Matter? Why or why not?

� When balancing equations:

� Write a coefficient _____________________ a substance's formula (not in the middle of the formula).

� You cannot change the ______________________________ in the formulas .

� Coefficients must be ____________________ numbers and ______________________ to lowest form.

� If the same polyatomic ion is on both sides of the equation, balance it like an ____________________.

� Balance oxygen, hydrogen and lone elements _________________________.

before

subscripts

whole reduced

element

last

����Let’s balance the following equations:

_____H2

+ _____O2

→→→→ _____H2O _____Ca + _____NaNO

3→→→→ _____Ca(NO

3)2

+ _____Na

� Try the following on your own:

____K + ____Cl2

→→→→ ____KCl ____CuSO4

+ ____Fe →→→→ ____Fe2(SO

4)3

+ ____Cu

____S + ____O2

→→→→ ____SO3

____HNO3

+ ____Ba(OH)2

→→→→ ____Ba(NO3)2

+ ____H2O

____AlBr3

+ ____Cl2

→→→→ ____AlCl3

+ ____Br2

____FeS + ____O2

→→→→ ____Fe2O

3+ ____SO

2

NO3

NaO

CaH

Product SideReactant SideElementProduct SideReactant SideElement

2 2

2 1

2

2

4

2

4 1 1

1 1

1 2

2

2

2

2

2

2 2

2 3 2

2 3 2 3

3 2 3

2 2

2 23.54 7

12 4

HH

OH H O O+ →

O? ?

H H

H H

+ O O →

HH

O

HH

O