1. Calculating Chemical Equations Why and How Many Atoms Bond

2. Chemical Equations A shorthand way to describe a chemical reaction using chemical symbols and formulæ

3. Chemical Equations Has three parts Reactants Substances present before the reaction Products Substances present after the reaction Yield Arrow Indicates the direction of a reaction Some reactions are reversible

4. Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction ReactantsProducts MgO + CCO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

5. Balancing Chemical Equations Equations must be balanced to observe the Law of Conservation of Matter Matter can not be created or destroyed under normal reactions If you begin a reaction with 5 g of Hydrogen, you must end up with 5 g of Hydrogen

6. A Balanced Chemical Equation Same numbers of each type of atom on each side of the equation Al + S Al 2 S 3 Not Balanced 2Al + 3S Al 2 S 3 Balanced

7. Balancing Chemical Equations Count atoms on both sides of the yield arrow Determine which elements are unequal Use coefficients to balance the number of atoms on both sides If you multiply one element in a compound, you multiply both elements in a compound You can treat Polyatomic Ions as one if they appear on both sides of the equation Go for the highest unequal elements first Leave solitary elements for last

8. Steps in Balancing An Equation Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O:Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

9. Balancing Chemical Equations Mg + N 2 Mg 3 N 2 Al + Cl 2 AlCl 3

10. Balancing Chemical Equations Fe 2 O 3 + C Fe + CO 2 Al + FeO Fe + Al 2 O 3 Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2

11. Types of Chemical Reactions Synthesis Two or more substances form one new substance H 2 +O 2  H 2 O N 2 +H 2  NH 3

12. Types of Chemical Reactions Decomposition One substance breaks down to form two or more new substances PbCO 3  PbO+CO 2 H 2 CO 3  H 2 O+CO 2

13. Types of Chemical Reactions Single Displacement One substance replaces another in a compound Li+AlCl 3  LiCl+Al

14. Types of Chemical Reactions Double Displacement Two substances “swap partners” in two compounds KOH+HBr  KBr+H 2 O NaOH + H 2 CO 3  Na 2 CO 3 + H 2 O

15. Types of Chemical Reactions Neutralization Double-displacement reaction where an acid and a base form a salt and water KOH+HBr  KBr+H 2 O NaOH + H 2 CO 3  Na 2 CO 3 + H 2 O

16. Acids and Bases Acids Taste Sour Have a pH of less than 7 Produce Hydronium H 3 O +1 in solution Have an “extra” H- on the beginning of the formula H 2 SO 4 – (Hydro)Sulfuric Acid H 3 PO 4 – (Hydro)Phosphoric Acid HNO 3 – (Hydro)Nitric Acid HCl – Hydrochloric Acid

17. Acids and Bases Bases Taste bitter Have a pH of more than 7 Produce Hydroxide OH –1 in solution Have an –OH on the end of the formula NaOH – Sodium Hydroxide KOH – Potassium Hydroxide Ca(OH) 2 – Calcium Hydroxide NH 4 OH – Ammonium Hydroxide

18. The Litmus Test Using an indicator can tell whether a substance is acidic or alkaline Litmus paper is a frequently-used indicator Acids turn BLUE litmus paper RED Bases turn RED litmus paper BLUE

19. Types of Chemical Reactions Combustion Where a carbon compound combusts with oxygen gas to form carbon dioxide and water CH 4 + O 2  CO 2 + H 2 O C 2 H 6 + O 2  CO 2 + H 2 O

20. Let’s get it started Some reactions require a little “jump start” to proceed Activation Energy Energy required to be applied to start a reaction Examples Applying friction to start a match The match causing a log to burn

23. Change in ENERGY Every reaction has some change in energy Two possibilities:

24. Endothermic – absorbs energy from the environment to complete reaction Feels “COLD” to its surroundings Products have MORE energy than the reactants

26. Exothermic – releases energy to the environment as the reaction proceeds Feels “HOT” to its surroundings Products have LESS energy than reactants

28. Speeding Up A Catalyst is a chemical that participates in a chemical reaction without being changed by the reaction Catalysts speed up reaction rates by acting as a “convenience” lowering the activation energy Organic catalysts are called ENZYMES

29. Hungry? Without enzymes, your cells would NEVER keep up with the energy demands

30. Slowing Down An Inhibitor also participates in a chemical reaction without being changed by the reaction Inhibitors slow down reaction rates by acting as an “inconvenience” raising the activation energy

31. Normal reaction / normal activation energy With a catalyst / lower activation energy

32. Counting Atoms Subscripts Coefficients Diatomic Molecules Polyatomic Ions Parenthesis Oxidation Numbers Binary Formulæ Criss-cross method Naming Rules Ionic Roman Numerals Covalent Prefixes Balancing Equations NEVER change subscripts Law of Conservation of Matter Types of Reactions Changes in Energy during reactions