Chapter 3: Types of Chemical
Reactions
Unit A: Matter and Chemical Change
What we already know…

Chemical reactions can be simple or complex

Chemical changes can be obvious or less noticeable

Chemical reactions can occur immediately or more
slowly
To describe chemical reactions, we use word equations
3.1 Word Equations

Word equations are always written in the same format



Left side of the equation lists the reactants
Right side of the equation lists the products
Arrow points from the reactants to the products
All Reactants

All Products
All the reactants and all the products are separated by a
plus sign (+)
reactant 1 + reactant 2
product 1 + product 2
3.1 Word Equations
Oxygen + food (glucose)
Continued
carbon dioxide + water + energy
Carbonic acid and calcium carbonate produce calcium hydrogen carbonate
3.2 Types of Reactions

In a simple composition reaction, two or more simple
elements combine to form a compound.
Element1 + Element 2
A
+
B
magnesium + oxygen
Compound
AB
magnesium oxide + light + thermal energy
Most simple composition reactions are exothermic
3.2 Types of Reactions

Continued
In a simple decomposition reaction, a reaction breaks a
compound into its component elements.
Compound
AB
water + electric energy
Element1 + Element 2
A
+
B
hydrogen gas + oxygen gas
Most decomposition reactions are endothermic
3.2 Types of Reactions

Combustion reactions always occur in the presence of
oxygen.


Continued
Candle wax burning in the presence of oxygen produces
carbon dioxide and water
Neutralization reactions are an acid reacting with a base
to produce a form of salt and water.
acid + base
salt + water
3.3 Formulas for Common Compounds
sulfur + zinc
zinc sulfide

A chemical name is the standard scientific name by
which each element or compound is known; established
by an internationally recognized naming system.

A chemical formula is the standard scientific symbol by
which each chemical element or compound is known.
S8(s) + 8Zn(s)
8ZnS(s)
3.3 Formulas for Common Compounds

Continued
Many chemical compounds are often identified by a
common name.

Easier to use and have existed before the international naming
system
Ethanol - alcohol
isopropyl alcohol – rubbing
alcolhol
Sodium bicarbonate – baking soda ethylene glycol - antifreeze
Methane – natural gas
sodium chloride - salt
Dihydrogen oxide - water
sucrose - sugar
3.4 Chemical Equations

The Law of Conservation of Mass states:
In a chemical reaction, matter is not created or destroyed. If you start a
reaction with 10g of reactants, you will end up with 10g of products.
~ Antoine Lavoisier (1743-1794)
vinegar + baking soda
sodium acetate + water + carbon dioxide gas
CH3COOH(aq) + NaHCO3(s)
NaC2H3O2(l) + H2O(l) + CO2(g)