Chemical equation the symbolic representation of a chemical reaction (process) wherein thereactant entities are on left side and change intoproduct entities on right-hand side

Chemical Equation SymbolsThe arrow can be read as “yields” or “produces”

The + sign reads as “and” or “plus”

Chemical Equation SymbolsThe arrow can be read as “yields” or “produces”Coefficients are the numbers in front of the formulasCoefficients can be changed to balance chemical equations

Subscripts tell us how many atoms or molecules we haveNEVER change subscripts when balancing chem. equations

Balancing Equations like solving a puzzle

Br2 + Al Al2Br6 (not balanced)

Balance using coefficients

Balancing Equations

Reactants Products

O2 + H2 H2O

Balancing Equations

Reactants Products

O2 + H2 H2O but this equation is not balanced

why not?

Balancing Equations

Conservation of Mass- Mass and/or Atoms are not Created or Destroyed during a chemical reaction. There must be the Same number of atoms on each side of the equation to balance the chemical equation.

Steps to Balance Chemical Equations1. Write unbalanced equation.

2. Count # atoms on each side.

3. Add coefficients to make #s of atoms equal.

Coefficient subscript = # of atoms

4. If necessary reduce coefficients to lowest possible ratio (never change subscripts)

5. Update and Double check atom balance!!!

Balancing Equations

Step 1. Write unbalanced equation

O2 + H2 H2O

Balancing Equations

Step 2. Count # of atoms on each side

O2 + H2 H2O

O = 2 0 = 1

H = 2 H = 2

Balancing Equations

3. Add coefficients to make # of atoms = on each side

O2 + H2 H2O

O = 2 0 = 1

H = 2 H = 2

Balancing Equations

3. Add coefficients to make # of atoms = on each side

O2 + 2 H2 2 H2O

O = 2 0 = 2

H = 4 H = 4

Balancing Equations

4. If necessary find lowest ratio (never change subscripts)

O2 + 2 H2 2 H2O

O = 2 0 = 2

H = 4 H = 4

Balancing Equations

5. Update and double check work

O2 + 2 H2 2 H2O

O = 2 0 = 2

H = 4 H = 4

Balancing Steps

1. Write the unbalanced equation.

Al + CuCl2 Cu + AlCl3

Balancing Steps1. Write the unbalanced equation.

2. Count atoms on each side.

Al + CuCl2 Cu + AlCl3

1 Al 1

1 Cu 1

2 Cl 3

Balancing Steps1. Write the unbalanced equation.

2. Count atoms on each side.

3. Add coefficients to make #s equal.

Coefficient subscript = # of atoms

Al + CuCl2 Cu + AlCl3

1 Al 1

1 Cu 1

2 Cl 3

Balancing Steps1. Write the unbalanced equation.

2. Count atoms on each side.

3. Add coefficients to make #s equal.

Coefficient subscript = # of atoms

Al + 3 CuCl2 Cu + 2 AlCl3

1 Al 2

3 Cu 1

6 Cl 6

Balancing Steps1. Write the unbalanced equation.

2. Count atoms on each side.

3. Add coefficients to make #s equal.

Coefficient subscript = # of atoms

2 Al + 3 CuCl2 3 Cu + 2 AlCl3

2 Al 2

3 Cu 3

6 Cl 6

Balancing Steps1. Write the unbalanced equation.

2. Count atoms on each side.

3. Add coefficients to make #s equal.

Coefficient subscript = # of atoms

4. Reduce coefficients to lowest possible ratio, if necessary.

5. Double check atom balance!!!

Helpful Tips• Balance one element at a time. Balance most

complicated compound first! • Update ALL atom counts after adding a

coefficient.• Balance (polyatomic ions) as (single units).

– “1 SO4” instead of “1 S” and “4 O”

• Balance most complicated compound first, balance

oxygen and hydrogen last (MINOH metals, ions, non-metals, oxygen, hydrogen)

• Ask yourself this question what am I forced to do to balance the equation???

Examples

____ Mg + ____ O2 ____ MgO

Examples

2 Mg + O2 2 MgO

Examples

____ Al + ____ S ____ Al2S3

Examples

2 Al + 3 S Al2S3

____ C3H8 +____ O2 ____ CO2 + ____ H2O

Examples

2 Al + 3 S Al2S3

C3H8 + 5 O2 3 CO2 + 4 H2O

More Examples

___ Al +____ H2SO4 ____Al2(SO4)3 +____ H2

More Examples

2 Al + 3 H2SO4 Al2(SO4)3 + 3 H2

Helpful Tips• Balance one element at a time.

• Update ALL atom counts after adding a coefficient.

• Balance (polyatomic ions) as (single units).– “1 SO4” instead of “1 S” and “4 O”

• Balance most complicated compound first, balance oxygen and hydrogen last

• Ask yourself this question what am I forced to do to balance the equation???

Steps to Predicting Products

1.Determine Reaction Type2.Predict Product Formulas3.Verify subscripts on Product Formulas4.Final Step Balance Equation

1. Determine Reaction Type2. Predict Product Formulas3. Verify subscripts on Product Formulas4. Final Step Balance Equation

Ag + Cu(SO4)

1. Determine Reaction Type2. Predict Product Formulas3. Verify subscripts on Product Formulas4. Final Step Balance Equation

Ag + Cu(SO4)