Balancing Chemical Equations

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```					                          Chapter 3- Equations and Stoichiometry
Balancing Chemical Equations

Chemical equations are used to convey both qualitative and quantitative info about a reaction.

Ex 1:

Heptane burns in oxygen to produce carbon dioxide and water.

The law of conservation of mass warrants the balancing of the equation.

Balancing is done by assuring there are the same number of atoms of each type on each side of the arrow.
NEVER CHANGE SUBSCRIPTS TO BALANCE EQUATIONS. Do write correct formulas first
before balancing is done.

For now , balancing will be a trial and error process.

However, there are tips.

1)   Balance metals first.
2)   Balance any element that is only in one place on each side first.
3)   Save H and O for last.
4)   Count polyatomic ions as units.
5)   The AP Exam will expect whole number coefficients. So use fractions first, then multiply each
coefficient by 2.

Ex 2: Write a balanced equation for the reaction between chlorous acid and solid cobalt (II) hydroxide to
produce water and aqueous cobalt (II) chlorite.

Assign- 3.1, 3, 5, 7, 8
Patterns of Chemical Reactivity

Combustion of a hydrocarbon

Combustion of an oxygenated fuel

Combustion of a reactive metal

Synthesis (Combination) between two elements

Ionic

Molecular

Synthesis between metal oxides and water

Synthesis between nonmetal oxides and water

Decomposition of a carbonate
Decomposition of chlorate

Decomposition of hydroxide

Decomposition of acid

Single replacement

Metathesis (Double replacement)

Assign- WS Predicting products.
Predicting products and Writing Equations

Predict the formulas of the product(s) and write a balanced equation for each of the following reactions.

1) NaCl(aq) +          AgNO3(aq) 

2) KClO3(s) 

3)    HIO (aq) + Ca(OH)2 (aq) 

4)    Na2O(s) +   H2O(l) 

5)    C2H5OH + O2 

6)    CuSO4 (aq) + Zn (s) 

7)    HC2H3O2(aq) +         Fe (s) 

8)    CuCO3 (s) 

9)    S8 (s) + O2 (g) 

10)   Ca(s) + O2 (g)

11) NaI(aq) +          Pb(NO3)2(aq) 

12) Ba(ClO3)2(s) 

13)   HNO2 (aq) + Fe(OH)3 (s) 

14)   Li2O(s) + H2O(l) 

15)   C4H10 (l)+ O2 (g)

16)   NiSO4 (aq) + Fe (s) 

17)   HBr (aq) +     Sn (s) 

18)   K2CO3 (s) 

19)   P4 (s) + O2 (g) 

20)   Mg(s) +     O2 (g)

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