1. Types of Chemical Rxns

2. Composition (Synthesis) Rxns Two or more substances react to form a single, more complex substance. Examples: 2 Hg + O 2 2HgO 2Ag + SAg 2 S Movie of Potassium + Bromine

3. Decomposition Reactions A Complex Substance is Broken Down (usually by heating) into 2 or more smaller substances Examples KClO 3 + heat KCl + O 2 2 2 3 BaCl 2  2H 2 O BaCl 2 + 2H 2 O Movie of Nitrogen TriIodide MnO 2 ªHªH ____ thermic endo H 2 O 2 (aq) H 2 O (l) + O 2 (g) MnO 2 Which Side does energy term go on? + heat 2 2

4. Single Replacement Rxns A single element takes the place of another element in a compound Examples: Zn + HCl H 2 + ZnCl 2 2 Cu + AgNO 3 Ag + Cu(NO 3 ) 2 2 2 Movie of Thermite Reaction

6. Double Replacement Rxn Sometimes called Exchange or Metathesis Rxns The ions in two aqueous compounds swap partners Examples: AgNO 3(aq) + NaCl (aq) AgCl ( 9 ) + NaNO 3(aq) Calcium chloride + Potassium Nitrate Potassium chloride + Calcium nitrate See formula Movie of sodium iodide + lead(II) nitrate

7. CaCl 2(aq) + KNO 3(aq) KCl (aq) + Ca(NO 3 ) 2 (s) 2 2 Back

8. Combustion Rxns A hydrocarbon reacts with oxygen to produce water and carbon dioxide Examples: CH 4 + O 2 H 2 O + CO 2 + heat 2 2 C 2 H 5 OH + O 2 H 2 O + CO 2 + heat 3 3 2 Balancing Tip: Do carbon 1 st, then hydrogen, then oxygen Usually used for the large amount of heat given off! ___thermic exo

9. Combustion Rxns Most reactions that we think of as ‘burning’ a fuel are combustion reactions Examples: Burning a log of Wood to heat your s’mores Burning Coal to heat water to create electricity at a power plant Grilling with Propane to heat your hot dog Burning Gasoline in your car to heat the air and push pistons Burning Oil in your furnace to heat your house Hydrocarbon

10. Combustion Rxns Some downsides to combustion reactions: ► Fossil Fuels are non-renewable resources  We are using them much faster than they are being produced  Eventually, we will run out of fossil fuels

11. Combustion Rxns Some downsides to combustion reactions: CO 2 is a greenhouse gas and increasing CO 2 levels contributes to global warming – (others are methane, water vapor, ozone, nitrous oxide) Our widespread burning of fossil fuels over the last hundred years has increased the earth’s CO 2 levels

12. Combustion Rxns Some downsides to combustion reactions: ► Combustion will be “incomplete” when not enough oxygen is present  Complete Combustion ► Hydrocarbon + O 2   Incomplete combustion results in CO, Carbon (soot), and nitrous oxides ► Hydrocarbon + O 2  C + CO +H 2 O + CO 2 ► CO is poisonous ► Nitrous oxides are bad for the environment (acid rain, smog) H2OH2O + CO 2

13. Combustion Rxns What can be done? ► Incomplete combustion can be improved by better designed burners / engines ► Catalytic converters in vehicle reduce CO ► “Scrubbers” placed in industrial exhaust systems can reduce nitrous oxides and CO None of these “fixes” cuts down or removes CO 2 emissions Balancing Combustion

17. Identify each reaction type (sr, dr, comp, decomp, combust) + + + O2O2 + C H + + + + C O2O2 O H A) B) C) D) E)

18. A Closer Look: Composition Rxns ► Aluminum + oxygen ► Calcium oxide + water ► Sulfur + oxygen

19. More Composition Rxns ► Sn + O 2 -----> ► Sodium + chlorine----> ► ► SO 3 + H 2 O --------> ► Lithium oxide + water--> ► ► Silicon + oxygen

20. More Composition Rxns Answers ► Sn + O2 ----->SnO2 ► 2Na + Cl2 ---> 2NaCl ► SO3 + H2O --------> H2SO4 ► Li2O + H2O ------> 2LiOH ► Si + O2 -----> SiO2

21. Decomposition Rxns ► CuSO 4  5H 2 O ► NaHCO 3 ► HNO 3

22. More Decomposition Rxns ► Na 2 CO 3 ----> ► MgO -----> ► MgSO 4  7H 2 O ----> ► Sr(NO 3 ) 2 ----> ► H 2 CO 3 ---->

23. More Decomposition Rxns (Answers) ► Na2CO3 ----> Na2O + CO2 ► 2MgO -----> 2Mg + O2 ► MgSO4*7H2O ----> MgSO4 + 7H2O ► Sr(NO3)2 ----> Sr(NO2)2 + O2 ► H2CO3 ----> H2O + CO2

24. Warm-Up: Complete and Balance C 2 H 6 + O 2  CO 2 + H 2 O 2 3 7 oxygens Can I get 7 Oxygens here?

25. 5 PBJ Sandwiches = ____ slices of bread 10 Balancing Combustion Rxns

26. 5 half PBJ Sandwiches = ____ slices of bread 5 5 pairs x ½ = 5 singles

27. Balancing Combustion Rxns 5 half O 2 molecules = ____ atoms of O 5 5 pairs x ½ = 5 singles

28. Balancing Combustion Rxns 7/2 O 2 molecules = ____ atoms of O 7 7 pairs x ½ = 7 singles

29. Warm-Up: Complete and Balance C 2 H 6 + O 2  CO 2 + H 2 O 2 3 7 oxygens 72 Total of 7 O’s

30. Your Turn: ► Complete # 10-12 on Page 14 in your packet