1. Chapter 10
Chemical Equations

2. A chemical reaction is a reaction in which at least one new substance is formed.
Example – Hydrogen and oxygen react to form water.

3. A chemical equation is a shorthand method of writing a chemical reaction using chemical symbols and formulas.
Example – H2 + O2  H2O

4. Symbols Used in Equations
(g) – gas
(cr) – crystalline solid
(l) – liquid
(aq) – aqueous solution

5. Law of Conservation of Mass
In an ordinary chemical reaction, mass can neither be created nor destroyed.
Mass of products must equal the mass of the reactants.

6. Balancing Chemical Equations
1. Count the number of atoms of each element on both sides of the equation.
2.Use coefficients to balance the equation.
3. Always use the lowest possible ratio of coefficients to balance.

7. Examples

8. Practice Website

9. Balancing NO-NO’s
Coefficients can only be added BEFORE a chemical symbol or formula.
NEVER change a subscript to balance an equation.

10. Signs a Chemical Reaction Has Occurred:
Color change
Liberation of a gas
Energy change
Formation of a precipitate
Change in odor

12. 5 Major Types of Chemical Reactions
1. Synthesis Reaction – 2 or more reactants combine to form one product.
Example-

13. Rust is the product of a synthesis reaction.

14. 2. Decomposition Reaction – the breakdown of one reactant into its components.
Example -

15. 3. Single Replacement Reaction – one element replaces another in a compound.
Example -

16. 4. Double Replacement Reaction – the positive and negative ions of two reactants exchange places.
Example-

17. Many times a precipitate is the result of a double replacement reaction.

18. 5. Combustion – the burning of an organic compound in oxygen to form CO2 and H2O and energy.
Example -

19. Welding is an example of a combustion reaction.

20. Practice – Classifying Reactions
Cl2 + 2KBr  KCl + Br2
2Ag2O  4Ag + O2
2Na + Cl2  2NaCl
PbCl2 + Li2SO4  PbSO4 + 2LiCl

21. Activote Quiz CaO + H2O  Ca(OH)2
This equation is an example of which type of chemical reaction:
Decomposition
Synthesis
Combustion
Single Replacement

22. LAB – Chemical Reactions

24. Writing Chemical Equations
7 Diatomic elements
Chlorine
Fluorine
Iodine
Bromine
Oxygen
Nitrogen
Hydrogen

25. Common Acids Sulfuric acid Nitric acid Carbonic acid Hydrochloric acid
Acetic acid
Phosphoric acid