Chemical Equations

Chemical Reactions - OVERVIEW change that occurs when atoms

rearrange themselves Can absorb or release energy

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Chemical equations used to describe chemical reactions

What is an equation in math?

What does it look like?

Chemical equations in science are similar!

Think!

Chemical Equation describes a chemical reaction

C + O2 CO2, The carbon reacts with oxygen to yield

carbon dioxide.

Parts of a Chemical Equation

This reads “carbon reacts with oxygen react to yield carbon dioxide”

C + O2 CO2REACTANTS

Molecules that are used in the reaction.

PRODUCTSMolecules that are

formed in the reaction.

The arrow is read as “yields”

Identify the reactants and products:

Chemical Equation Name theElements

Name theREACTANTS

Name thePRODUCTS

2Na + Cl2 → 2NaCl Sodium, Chlorine

Sodium, Chlorine

Sodium Chloride (salt)

CO2 + H2 CH4 + H2O

2H2 + O2 2H2O

4Al + 3 O2 2Al2O3

Key: CH4 = methane, NaCl= Sodium Chloride, Al2O3 = Aluminum Oxide

Law of Conservation of Mass

Matter can not be created or

destroyed, although it may be

rearranged.

Lavoisier, 1788

Chemical EquationsBecause of

“Conservation of Mass”, chemical equations must be balanced

Must have same number of each element on both sides of equation

Lavoisier, 1788

2H2 + O2 2H2O What elements do you

have?

Balanced or Unbalanced?

HydrogenOxygen

HydrogenOxygen

A chemical equation must have the same number of atoms of each element on either

side of the arrow in order to be balanced

2H2 + O2 2H2O How many atoms of each elements

do you have?

Balanced or Unbalanced?A chemical equation must have the same type and amount of atoms on either side of the arrow in order to

be balanced

HydrogenOxygen

HydrogenOxygen

A chemical equation must have the same type and amount of atoms on either side of the arrow in order to

be balanced

= 4

= 2

= 4

= 2BALANCED

Al + Br2 Al2Br6 What elements do you have?

Balanced or Unbalanced?

AluminumBromine

AluminumBromine

Balanced or Unbalanced?

= 1

= 2 = 6

= 2

Al + Br2 Al2Br6

How many atoms of each elements do you have?

AluminumBromine

AluminumBromine

*UNBALANCED*

Chemical Reactions & Equations – PRACTICE!

K3PO4 + 2HCl 2KCl + H3PO4 Is this equation balanced?

K = 3P = 1

O = 4H = 2

K = 2P = 1O = 4H = 3

No: K and H are not the same on both

sides of the equation

Cl = 2

Cl = 2

Reactants = Products