1. Law of Conservation of Mass through Balancing Equations

2. Putting chemical changes into words
Chemical Equations
Putting chemical changes into words

3. The burning of methane gas in oxygen is:
Equation Example:
The burning of methane gas in oxygen is:
CH4 + 2 O2 → CO2 + 2 H2O

4. Review: Chemical Formulas
Shows the elements & number of atoms of each element in a molecule
H2SO4
Elements
Hydrogen; 2 atoms
Sulfur: 1 atom
Oxygen: 4 atoms
7 atoms total
Subscript

5. Coefficients A formula may begin with a number.
If there is no number, then “1” is understood to be in front of the formula.
This number is called the coefficient.
The coefficient represents the number of molecules of that compound or atom needed in the reaction.
For example:
2H2SO4 – 2 molecules of Sulfuric Acid

6. Coefficients 2H2SO4 – 2 molecules of Sulfuric Acid
A coefficient is distributed to ALL elements in a compound
2 – H2 (for a total of 4 H atoms)
2 – S (for a total of 2 S atoms)
2 – O4 (for a total of 8 O atoms)

7. Define the Law of Conservation of Mass
Matter cannot be created nor destroyed.
In a chemical reaction, the mass of the products equals the mass of the reactants.
The number of atoms in the reactant side must equal the number of atoms in the product side.
No new elements appear.
No new elements disappear.

8. Balancing Equations Step 1: Write the equation
Step 2: Draw a line through the middle of the equation.
Step 3: Write down the reactants and products. Plus how many atoms you have of each.
Step 4: Look for numbers that are not the same and balance to the highest number.
Step 5: Using multiplication multiply the small number by a number that will give you the same number on the opposite side.
Step 6: This sometimes will change your formula so just adjust.
Step 7: When you are done look at both side and see if your numbers match, if they don’t start the process again.
H N2  NH3
Ag + S8  Ag2S
CO2 + H20 C6H1206+ O2