1. Decomposition, Synthesis/Formation, & Combustion Reactions

2. Reaction Type #3 - Decomposition Occurs when a single compound breaks down into two or more components Occurs when a single compound breaks down into two or more components Energy is required for them to occur Energy is required for them to occur Reactants will always be: Reactants will always be: 1 compound 1 compound Products will always be: Products will always be: ALWAYS more products than reactants ALWAYS more products than reactants 2 components (either compounds or elements) 2 components (either compounds or elements) i.e.: i.e.: AB  A + B AB  A + B

3. Decomposition Example: One unit breaks down into its component parts One unit breaks down into its component parts i.e. – The marriage of Brad Pitt and Jennifer Aniston breaks into the single Brad Pitt and the single Jennifer Aniston i.e. – The marriage of Brad Pitt and Jennifer Aniston breaks into the single Brad Pitt and the single Jennifer Aniston

4. Decomposition Examples i.e.:Ag 2 O  ________ + __________ i.e.: MgO  ________ + ___________

5. Reaction Type #4 – Synthesis/Formation Occurs when two or more components come together to form one compound Occurs when two or more components come together to form one compound Energy is released when these reactions occur Energy is released when these reactions occur Reactants will always be: Reactants will always be: ALWAYS more reactants than products! ALWAYS more reactants than products! 2 or more components (either elements or compounds) 2 or more components (either elements or compounds) Products will always be: Products will always be: 1 single compound 1 single compound i.e.: i.e.: A + B  AB A + B  AB

6. Synthesis/Formation Example Two individual components coming together to form one unit Two individual components coming together to form one unit i.e. – single Robert Pattinson and a single Kristen Stewart come together to form a totally awesome Twilight couple OMG OMG LOL NEW MOON! LIKE TOTALLY AWESOME! i.e. – single Robert Pattinson and a single Kristen Stewart come together to form a totally awesome Twilight couple OMG OMG LOL NEW MOON! LIKE TOTALLY AWESOME!

7. Special Cases for Decomposition & Synthesis/Formation Reactions Decomposition and Synthesis/Formation Reactions are opposite processes (duh) Decomposition and Synthesis/Formation Reactions are opposite processes (duh) Special Case #1: Special Case #1: A non metal oxide + water combine to form an acid A non metal oxide + water combine to form an acid i.e.: SO 3 (g)+ H 2 O (l)  H 2 SO 4 (aq) i.e.: SO 3 (g)+ H 2 O (l)  H 2 SO 4 (aq) AND an acid will decompose to form a non-metal oxide + water AND an acid will decompose to form a non-metal oxide + water i.e.: H 2 SO 4 (aq)  SO 3 (g)+ H 2 O (l) i.e.: H 2 SO 4 (aq)  SO 3 (g)+ H 2 O (l)

8. Special Cases for Decomposition & Synthesis/Formation Reactions Special Case #2 Special Case #2 A metal oxide + water combine to form a metal hydroxide A metal oxide + water combine to form a metal hydroxide i.e.: CaO (s) + H 2 O (l)  Ca(OH) 2 (aq) i.e.: CaO (s) + H 2 O (l)  Ca(OH) 2 (aq) A metal hydroxide will decompose into a metal oxide + water A metal hydroxide will decompose into a metal oxide + water i.e.: Ca(OH) 2 (aq)  CaO (s)+ H 2 O (l) i.e.: Ca(OH) 2 (aq)  CaO (s)+ H 2 O (l)

9. Special Cases for Decomposition & Synthesis/Formation Reactions Special Case #3: Special Case #3: All carbonates decompose into carbon dioxide and an oxide All carbonates decompose into carbon dioxide and an oxide i.e.: CaCO 3  CaO + CO 2 i.e.: CaCO 3  CaO + CO 2 Vice versa for synthesis/formation reactions Vice versa for synthesis/formation reactions Special Case #4: Special Case #4: All chlorates decompose into oxygen and a binary salt All chlorates decompose into oxygen and a binary salt i.e.: 2KClO 3  2KCl + 3O 2 i.e.: 2KClO 3  2KCl + 3O 2 Vice versa for synthesis/formation reactions Vice versa for synthesis/formation reactions

10. States for Synthesis & Decomposition Reactions Pure elements: Pure elements: Simply refer to the periodic table for their states Simply refer to the periodic table for their states Water: Water: Pure liquid Pure liquid Compounds: Compounds: No way of predicting the states with accuracy unless you actually do the experiment No way of predicting the states with accuracy unless you actually do the experiment The question MAY give you more information, so use that if you can The question MAY give you more information, so use that if you can If not, use some common sense and prior experience: If not, use some common sense and prior experience: i.e. – Acids are aqueous; etc. i.e. – Acids are aqueous; etc.

11. Reaction Type #5 - Combustion Also known as BURNING Also known as BURNING Hydrocarbon Hydrocarbon Compound composed of only carbon and hydrogen (and sometimes oxygen) Compound composed of only carbon and hydrogen (and sometimes oxygen) Reactants will always be: Reactants will always be: Hydrocarbon + oxygen Hydrocarbon + oxygen Products will always be: Products will always be: Carbon dioxide + water Carbon dioxide + water

12. States for Combustion Reactions Hydrocarbon: Hydrocarbon: No way of predicting the states with accuracy unless you actually do the experiment No way of predicting the states with accuracy unless you actually do the experiment The question MAY give you more information, so use that if you can The question MAY give you more information, so use that if you can If not, use some common sense and prior experience: If not, use some common sense and prior experience: i.e. – Sugar is a solid, etc. i.e. – Sugar is a solid, etc. Oxygen: Oxygen: Gas Gas Carbon Dioxide: Carbon Dioxide: Gas Gas Water: Water: Gas (water vapour; remember, combustions are hot) Gas (water vapour; remember, combustions are hot) Or liquid Or liquid

13. Examples i.e.: C 6 H 6 + O 2  i.e.: C 6 H 12 O 6 + O 2 