Chemical Reactions

Demo 1

2 H2O2 2 H2O + O2 + Heat

Reactants Products

Demo 2

Methane Bubbles!CH4 + 2O2 CO2 + 2H2O + Heat

What is a Chemical Reaction?

A chemical reaction- is a change in which one or more substances are converted into new substances.

An example of this would be a rusty nail. A chemical reaction between the iron in the steel and the oxygen in the atmosphere causes rust.

Other examples: lighting a match, start a car, eat dinner or even walking the dog.

Identify the reactants and the products in the following chemical equations.

Chemical Equation Reactants Products

2 Na + S Na2S C + O2 CO2

CaO O2 + 2 Ca

Types of Reactions

Synthesis/CombinationDecompositionSingle DisplacementDouble DisplacementCombustion

Synthesis/CombinationOccurs when two or more

substances combine to form one substance

A + B AB

Most synthesis reactions involve two elements combining to form a compound

Decomposition of Nitrogen triiodine

Nitrogen triiodine decomposition video

Single Replacement ReactionExploding Egg Video (Single Repl

acement)

Double ReplacementDouble Replacement Reactions Vi

deo

Why is it important to balance reactions?

Conservation of MassTotal mass of products equals

total mass of reactantMass is conserved, not created or

destroyed

Law of Conservation of Mass Video

Balancing EquationsBalancing an equation means: changing

coefficients so a chemical equation has the same number of atoms on both sides.

4Al + 3O2 2Al2O3 Coefficients are the numbers that show:

how many atoms or molecules of each substance are used or produced.

4Al + 3O2 2Al2O3

Balancing EquationsSubscripts are numbers that show there is

more than one atom of a certain type in a molecule of a substance

Balance this equation: Fe + 02 FeO Fe O

Steps for balancing an Equation1. Write a chemical equation using formulas

and symbols. Fe (s) + O2 FeO (s)2. Count the atoms in the reactants and

products. reactants products Fe O

3. Choose coefficients to balance the equation.

2Fe(s) + 02 2 FeO(s)

4. Check the number of atoms on each side of the equation.

1. Group Balancing!

2. Let’s review!

2. Pair Balancing

1. Motivational Video

3. Let’s Review

1. Individual Balancing

2. Let’s Review

Reminder Complete Homework practice

problems. ◦Due tomorrow!

Balancing Quiz 1st thing tomorrow!