This is a presentation of my Chemistry course. Chapter 5 about chemical reactions and equations.

1. Chemical Reactions and
Equations

2. • Chemical Reactions are associated with
chemical change.
• Whenever a chemical change occurs
chemical reaction is said to take place.
• Chemical reactions are usually irreversible
and a new product is formed.

3. • There are five main signs that indicate a
chemical reaction has taken place.
Change in color Evolution of gas Production of light Formation of a
solid
Absorption or
release of heat

4. • A chemical reaction is the conversion of one substance
or set of substances into another.
• Any substance that we start with is a reactant.
• A new substance that forms during the reaction is a
product.
methane + oxygen carbon dioxide + water
Reactant Product

5. • A chemical equation is a symbolic
representation of a chemical reaction.
For example:
The reactants are written on the left side, and
the products are written on the right side.
An arrow shows the direction of reaction.

6. • The equation must represent known facts
• The equation must contain the correct
formulas for the reactants and products.
• The physical state—solid(s), liquid(l), gas(g),
or aqueous solution(aq)--- is shown for each
reactant and product.
• The equation must be balanced.

7. • The number of atoms of each element is
the same in the products as in the
reactants.
• For example:

11. Four basic types of the chemical reactions

12. • When a compound undergoes a decomposition
reaction, it breaks down into the elements of which it is
composed or into simpler compounds.

14. • In a combination reaction, two elements, an element
and a compound, or two compounds react to produce a
single compound.

16. • In a single-displacement reaction, a free element
displaces another element from a compound to produce
a different compound and a different free element.

18. • In each reaction, two compounds exchange parts to
form two new compounds is called a double-
displacement reaction.