1. 2B.5 Notes Chemical equation
10/16/17

2. Chemical Changes Remember:
Chemical changes (or reactions) occur when a change in matter produces a new substance
Color Change
Temperature Change
Formation of Precipitate
Formation of Gas

3. Chemical Equation
A way to represent a chemical reaction using element symbols.
Chemical symbols have 2 sides
Reactant (Left Side)
Product (Right Side)
The arrow represents the reaction taking place; The reactant “ yields” or ”makes”
2H + O2  2H2O

4. Reactant Substances broken apart or combined in a chemical reaction
2H + O2  2H2O

5. Product New substances formed when a chemical reaction occurs
2H + O2  2H2O

6. Law of Conservation of Matter
The amount of matter does NOT change during a chemical reaction
Atoms are rearranged to form new substances
This means that the total mass of the reactant is equal to the total mass of the product.

7. Balanced Chemical Equation
Has the same number of each kind of atom on the reactant side as on the product side.
To be balanced you have to look at the Subscript and the Coefficient

8. That means there are 2 Hydrogen Atoms present.
Subscript
Remember:
The subscript is the tiny number behind the element.
It tells you home many of that atoms are present
2H2O
That means there are 2 Hydrogen Atoms present.

9. Coefficient
The number that comes before the chemical formula and indicates the number of particles present in the reaction.
2H2O
That means: H2O + H2O

10. How do I read a Chemical equation?
Chemical Equation: 2H2 + O2  2H2O Multiply the Coefficient in front of the chemical formula by the Subscript 2 x 2 = 4 2H2 + O2  2H2O This means there are 4 Hydrogen Atoms in the Reactant 2 x 1 = 2 2H2 + O2  2H2O1 This means there are 2 Oxygen Atoms in the Reactant

11. How do I balance a Chemical Equation?
Balance Metals
Balance Nonmetals (Except Hydrogen & Oxygen)
Balance Hydrogen
Balance Oxygen

12. How do I balance a Chemical Equation?
Determine if the number of each kind of atom on the left side (Reactant) of the arrow is equal to the number on the right side (Product) of the arrow.
H2 + O2  H2O
No! Because there is only 1 Oxygen in the Product but 2 Oxygen in the reactant.
So I add a coefficient in front of my Product.
H2 + O  2H2O

13. How do I balance a Chemical Equation?
H2 + O  2H2O Now there are too many Hydrogen Atoms in the product and not enough in the reactant. So I need to add a coefficient to my reactant. 2H2 + O  2H2O

14. How do I balance a Chemical Equation?
2H2 + O2  2H2O
Is my equation balanced?
Yes!
There are 4 Hydrogen Atoms in my reactant and 4 Hydrogen Atoms in my product
There are 2 Oxygen atoms in my reactant and 2 Oxygen Atoms in my Product.