1. Chemical Reactions

2. What a chemical equation looks like: yields 2 Na (s) + Cl 2 (g)  2 NaCl (s) coefficients symbols state of matter

3.  How to describe a chemical change 1. Word equations  Reactants  Products  Examples: iron + oxygen  iron (III) oxide

4. 2. skeleton equation  First step in an chemical equation  Does not show amounts  Uses common symbols

5. 3. “Common symbols” a. solid (s) b. liquid (l) c. gas (g) d. aqueous solution (aq)- substance dissolved in water

6. e. catalyst 1. Speeds up the reaction 2. Is not used up 3. Written on the arrow Δ –heat catalyst MnO 4

7. f. Examples MnO 2 H 2 O 2 (aq) ----> H 2 O (l) + O 2 (g) 4. skeleton examples a. Iron(III) oxide reacts with carbon monoxide to produce iron and carbon dioxide

8. b. Heating potassium chlorate in the presence of MnO 2 produces oxygen gas and potassium chloride as a solid

9.  Balancing Chemical Equations 1. 2H 2 (g) + O 2 (g)  2 H 2 O (l) 2. Only numbers you may write are coefficients. 3. YOU MAY NEVER CHANGE SUBSCRIPTS!

10. 4. Leave H and O go until last. 5. Reduce if possible, lowest whole number ratios. 6. Examples: a. AgNO 3 + H 2 S  Ag 2 S + HNO 3

11. b. HCl + NaOH --> NaCl + H 2 O c. Al(OH) 3 + H 2 CO 3 --> Al 2 (CO 3 ) 3 + H 2 O d. Al + S 8 --> Al 2 S 3 e. N 2 + H 2 --> NH 3

12. Types of Chemical Reaction A. Combination reaction (synthesis) 1. Two or more elements combine to form ONE product 2. A + X  AX 2K(s) + Cl 2 (g)  2KCl (s)

13. B. Decomposition 1. one reactant breaks into products 2. AX  A + X 3. Ex. H 2 CO 3 (aq)  H 2 O (l) + CO 2 (g)

14. C. Single displacement 1. A + BX  AX + B element + compound  compound + element 2. Ex. Cu + 2 AgCl  CuCl 2 + 2 Ag

15. D. Double displacement 1. positive ions switch with positive ions 2. AX + BY  BX + AY 3. NaOH + HCl  NaCl + H 2 O

16. E. Combustion 1. always a hydrocarbon (C and H) added to oxygen 2. products are always carbon dioxide and water 3. Ex. 2 C 2 H 6 + 7 O 2  4 CO 2 + 6H 2 O

17. F. See packet to do this

18. G. Net Ionic Equation 1. Spectator ions – “watch” do not really do anything 2. Break only (aq) ions apart 3. Do not break (s) apart

19. 4. Examples: a.AgNO 3 (aq) + NaCl(aq)  AgCl(s) + NaNO 3 (aq) b.Pb (s) + AgNO 3 (aq)  Ag (s) +Pb(NO 3 ) 2 (aq)

20. F. Combustion reactions 1. always reacts with oxygen 2. hydrocarbon (some form of CH) plus oxygen always gives carbon dioxide and water

21. 3. Examples: a. C 6 H 6 + O 2 