1. Chemical Equations

2. Chemical Reactions - OVERVIEW change that occurs when atoms rearrange themselves Can absorb or release energy  Heat  Light  Sound Chemical equations used to describe chemical reactions

3. What is an equation in math? What does it look like? Chemical equations in science are similar! Think!

4. Chemical Equation describes a chemical reaction C + O 2  CO 2, The carbon reacts with oxygen to yield carbon dioxide.

5. Parts of a Chemical Equation This reads “carbon reacts with oxygen react to yield carbon dioxide” C + O 2  CO 2 REACTANTS Molecules that are used in the reaction. PRODUCTS Molecules that are formed in the reaction. The arrow is read as “yields”

6. Identify the reactants and products: Chemical Equation Name the Elements Name the REACTANTS Name the PRODUCTS 2Na + Cl 2 → 2NaCl Sodium, Chlorine Sodium Chloride (salt) CO 2 + H 2  CH 4 + H 2 O 2H 2 + O 2  2H 2 O 4Al + 3 O 2  2Al 2 O 3 Key: CH 4 = methane, NaCl= Sodium Chloride, Al 2 O 3 = Aluminum Oxide

7. Law of Conservation of Mass Matter can not be created or destroyed, although it may be rearranged. Lavoisier, 1788

8. Chemical Equations Because of “ Conservation of Mass”, chemical equations must be balanced Must have same number of each element on both sides of equation Lavoisier, 1788

9. 2H 2 + O 2 2H 2 O  What elements do you have? Balanced or Unbalanced? Hydrogen Oxygen Hydrogen Oxygen A chemical equation must have the same number of atoms of each element on either side of the arrow in order to be balanced

10. 2H 2 + O 2 2H 2 O  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 Hydrogen Oxygen Hydrogen Oxygen 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 = 2 BALANCED

11. Al + Br 2 Al 2 Br 6  What elements do you have? Balanced or Unbalanced? Aluminum Bromine Aluminum Bromine

12. Balanced or Unbalanced? = 1 = 2= 6 = 2 Al + Br 2 Al 2 Br 6 How many atoms of each elements do you have? Aluminum Bromine Aluminum Bromine *UNBALANCED*

13. Chemical Reactions & Equations – PRACTICE! K 3 PO 4 + 2HCl  2KCl + H 3 PO 4 Is this equation balanced? K = 3 P = 1 O = 4 H = 2 K = 2 P = 1 O = 4 H = 3 No: K and H are not the same on both sides of the equation Cl = 2 Reactants = Products