1. Types of Chemical Reactions

2. basic types of reactions
Good News!
Of all the millions of possible chemical reactions, there are only 5
basic types of reactions

3. Synthesis Two or more reactants combine to form a product: A + B C
C O CO2

4. Decomposition
The reverse of synthesis: A compound breaks down into two or more simpler substances
A B C
CO C O2

5. Single Replacement
A “single” element replaces another element in a compound
A + BX B + AX
Na + AgNO Ag + NaNO3

6. When will single replacement reactions occur?
Use Table J for single replacement reactions
The higher the element is on the table, the more reactive it is. A reactive element wants to react, and form a compound. It will “bump” a less reactive element out of the compound and take its place.

7. Single Replacement
In this example, Na is more reactive than Ag, so Na bumps Ag out of the nitrate compound and takes its place.
Na + AgNO Ag + NaNO3

8. Double Replacement
Two aqueous ionic compounds (dissolved in water) switch positive ions to produce either a precipitate, a gas, or a molecular compound (like water)
AB CD AD CB
AgNO3(aq)+ NaCl(aq) AgCl(s) + NaNO3(aq)

9. Double Replacement Use Table F to determine if a precipitate will form
AB CD AD CB
AgNO3(aq)+ NaCl(aq) AgCl(s) + NaNO3(aq)

10. Combustion Hydrocarbon and oxygen yields carbon dioxide
and water and heat
CH O CO2 + H2O + heat

11. Balancing Equations
Mass is always conserved in a chemical reaction

12. N + O NO
N + O NO2

13. H O H2O
Is mass conserved in this equation?
NO!
Reactants:
Products:
2 H
1 O
2 H
2 O

14. How to Balance an equation
Step 1. Place a box around all compounds
H O H2O
Step 2. DO NOT make any changes to the
compounds inside each box!!!!!!

15. How to Balance an equation
Step 3. Place coefficients in front of each
box to show conservation of mass.
Everything inside the box will be multiplied
by this number.
H O H2O 2
Products:
Reactants:
4 H
2 O
2 H
2 O

16. How to Balance an equation
Step 3. Place coefficients in front of each
box to show conservation of mass.
Everything inside the box will be multiplied
by this number. 2
H O H2O 2
Products:
Reactants:
4 H
2 O
4 H
2 O

17. How to Balance an equation
Step 4. Count the types of atoms on both
sides of the equation. The atoms on the reactant
side must be the same as the atoms on the
product side 2
H O H2O 2
Products: =
Reactants:
4 H
2 O
4 H
2 O

18. Helpful Hints for balancing
Balance one type of atom at a time
Balance atoms that appear only once on each side of the equation first
Balance oxygen and hydrogen last
It is an iterative process. Be Patient!

19. Balance these….
Fe + O Fe2O3
Mg + HCl H MgCl2

20. Unknown reactants or products
Since mass is always conserved, this principle can be used to find unknown parts of a chemical reaction
Count the atoms on both sides of the equation and determine what atoms are missing from one side……

21. Unknown reactants or products
2 Na + 2H2O X NaOH
Reactants:
Products:
2 Na H
2 O
2 Na
2 H
2 O
X must be H2

22. Unknown reactants or products
2 Na + 2H2O H NaOH
Reactants:
Products:
2 Na H
2 O
2 Na
2 H
2 O
X must be H2

23. Finding Missing Mass
In a similar way to finding missing compounds, missing mass can also be found since mass is always conserved.

24. Given the following balanced equation:
2 KClO KCl O2
If 103 g of KClO3 decomposed to form 62.7 g of KCl,
how many grams of oxygen gas are formed?

25. 2 KClO KCl O2
103 g = g x
103 g – 62.7 g = x
40.3 g = x