Types of Reactions Including reaction prediction

Generals about writing Equations  Reactants on the left and products on the right  Symbols - see text for symbols that are included in equations.  Ex: g for gas, l for liquid, s for solid  Downward arrow for precipitate, aq for aqueous  Catalyst goes above the arrow  KI  Ex H 2 O 2(aq) ---> H 2 O (l) + O 2(g)  Diatomic Molecules - BrINClHOF  Elemental state - Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2  Reactants on the left and products on the right  Symbols - see text for symbols that are included in equations.  Ex: g for gas, l for liquid, s for solid  Downward arrow for precipitate, aq for aqueous  Catalyst goes above the arrow  KI  Ex H 2 O 2(aq) ---> H 2 O (l) + O 2(g)  Diatomic Molecules - BrINClHOF  Elemental state - Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2

1. Synthesis (Combination)  Two or more substances react to form a single substance  R + S --> RS  Ex) SO 3(g) + H 2 O (l) --> H 2 SO 4(aq)  Usually gives off energy when forming bonds  Example: Write the balanced equation for: magnesium ribbon reacting with oxygen  Mg (s) + O 2(g) ---> MgO (s)  2 Mg (s) + O 2(g) --> 2MgO (s)  Two or more substances react to form a single substance  R + S --> RS  Ex) SO 3(g) + H 2 O (l) --> H 2 SO 4(aq)  Usually gives off energy when forming bonds  Example: Write the balanced equation for: magnesium ribbon reacting with oxygen  Mg (s) + O 2(g) ---> MgO (s)  2 Mg (s) + O 2(g) --> 2MgO (s)

1. Synthesis (Combination)  Your turn. Write balanced equations for the following:  Aluminum (s) reacts with oxygen (g)  Hydrogen (g) reacts with oxygen (g)  Answers:  4 Al (s) + 3 O 2 ---> 2 Al 2 O 3(s)  2 H 2(g) + O 2(g) ---> 2 H 2 O (l)  Your turn. Write balanced equations for the following:  Aluminum (s) reacts with oxygen (g)  Hydrogen (g) reacts with oxygen (g)  Answers:  4 Al (s) + 3 O 2 ---> 2 Al 2 O 3(s)  2 H 2(g) + O 2(g) ---> 2 H 2 O (l)

2. Decomposition  A single compound is broken down into simpler products  RS --> R + S  Ex) BCl 3 --> B + Cl 2  Requires energy to break chemical bonds (heat, light, electricity)  Example - Write the balanced equation for mercury (II) oxide decomposing;  HgO --> Hg + O 2  2HgO --> 2Hg + O 2  A single compound is broken down into simpler products  RS --> R + S  Ex) BCl 3 --> B + Cl 2  Requires energy to break chemical bonds (heat, light, electricity)  Example - Write the balanced equation for mercury (II) oxide decomposing;  HgO --> Hg + O 2  2HgO --> 2Hg + O 2

2. Decomposition  Your turn. Write balanced equations for the following:  The decomposition of water  The decomposition of lead (IV) oxide  Answers  2 H 2 O (l) --> 2 H 2(g) + O 2(g)  PbO 2(s) --> Pb (s) + O 2(g)  Your turn. Write balanced equations for the following:  The decomposition of water  The decomposition of lead (IV) oxide  Answers  2 H 2 O (l) --> 2 H 2(g) + O 2(g)  PbO 2(s) --> Pb (s) + O 2(g)

3. Single Replacement Reactions  An element replaces an element of a compound  T + RS --> TS + R  Ex) Zn (s) + H 2 SO 4(aq) --> ZnSO 4(aq) + H 2(g)  A metal may replace a metal or a nonmetal may replace a nonmetal  Activity Series - list of metal in order of decreasing activity  Nonmetals reactivity decreases as you go down the periodic table  This is limited to the halogens -group 7A  An element replaces an element of a compound  T + RS --> TS + R  Ex) Zn (s) + H 2 SO 4(aq) --> ZnSO 4(aq) + H 2(g)  A metal may replace a metal or a nonmetal may replace a nonmetal  Activity Series - list of metal in order of decreasing activity  Nonmetals reactivity decreases as you go down the periodic table  This is limited to the halogens -group 7A

3. Single replacement reactions  Ex) Write the balanced equation when aluminum reacts with sulfuric acid  Al (s) + H 2 SO 4(aq) --> Al 2 (SO 4 ) 3(s) + H 2(g)  2Al (s) + 3H 2 SO 4(aq) --> Al 2 (SO 4 ) 3(s) + 3H 2(g)  Ex) Write the balanced equation when aluminum reacts with sulfuric acid  Al (s) + H 2 SO 4(aq) --> Al 2 (SO 4 ) 3(s) + H 2(g)  2Al (s) + 3H 2 SO 4(aq) --> Al 2 (SO 4 ) 3(s) + 3H 2(g)

3. Single replacement reactions  Your turn. Write balanced equations for the following:  When chlorine reacts with potassium iodide  When copper (assume Cu 2+ ) is added to Iron (II) Sulfate  Answers  Cl 2(g) + 2 KI (aq) --> 2 KCl (aq) + I 2  Cu + FeSO 4 --> no reaction (no rxn)  Your turn. Write balanced equations for the following:  When chlorine reacts with potassium iodide  When copper (assume Cu 2+ ) is added to Iron (II) Sulfate  Answers  Cl 2(g) + 2 KI (aq) --> 2 KCl (aq) + I 2  Cu + FeSO 4 --> no reaction (no rxn)

4. Double Replacement  Exchange of positive ions between two compounds. Just swap the positive ions and write the new formula.  R + S - + T + U - --> R + U - + T + S -  Ex) FeS (s) + 2HCl (aq) --> H 2 S (g) + FeCl 2(aq)  Ex) Write the balanced equation for barium chloride added to potassium carbonate  BaCl 2(aq) + K 2 CO 3(aq) --> BaCO 3(s) + KCl (aq)  BaCl 2(aq) + K 2 CO 3(aq) --> BaCO 3(s) + 2 KCl (aq)  Exchange of positive ions between two compounds. Just swap the positive ions and write the new formula.  R + S - + T + U - --> R + U - + T + S -  Ex) FeS (s) + 2HCl (aq) --> H 2 S (g) + FeCl 2(aq)  Ex) Write the balanced equation for barium chloride added to potassium carbonate  BaCl 2(aq) + K 2 CO 3(aq) --> BaCO 3(s) + KCl (aq)  BaCl 2(aq) + K 2 CO 3(aq) --> BaCO 3(s) + 2 KCl (aq)

4. Double Replacement  Your turn. Write balanced equations for the following.  Iron (III) Sulfide reacting with hydrochloric acid  Answer  Fe 2 S 3(s) + 6 HCl (aq) --> 2 FeCl 3(aq) + 3 H 2 S (g)  Your turn. Write balanced equations for the following.  Iron (III) Sulfide reacting with hydrochloric acid  Answer  Fe 2 S 3(s) + 6 HCl (aq) --> 2 FeCl 3(aq) + 3 H 2 S (g)

5. Combustion Reactions  Oxygen reacts with another substance, often producing heat and light  Often involve hydrocarbons  Compounds of hydrogen and carbon  Combustion of hydrocarbons produces a lot of energy, therefore, hydrocarbons are used as fuels.  Examples: methane, propane, butane, octane  Oxygen reacts with another substance, often producing heat and light  Often involve hydrocarbons  Compounds of hydrogen and carbon  Combustion of hydrocarbons produces a lot of energy, therefore, hydrocarbons are used as fuels.  Examples: methane, propane, butane, octane

5. Combustion Reactions  Two types of combustion  1. Complete combustion  C x H y + O 2(g) --> CO 2(g) + H 2 O (g) + energy  2. Incomplete combustion  Two more products: CO and C  C x H y + O 2(g) --> CO 2(g) + H 2 O (g) + CO (g) + C (s) + energy  Two types of combustion  1. Complete combustion  C x H y + O 2(g) --> CO 2(g) + H 2 O (g) + energy  2. Incomplete combustion  Two more products: CO and C  C x H y + O 2(g) --> CO 2(g) + H 2 O (g) + CO (g) + C (s) + energy

5. Combustion Reactions  Ex) Write a balanced equation for the complete combustion of C 3 H 8.  C 3 H 8(g) + O 2(g) --> CO 2(g) + H 2 O (g) + energy  C 3 H 8(g) + 5 O 2(g) --> 3 CO 2(g) + 4H 2 O (g) + energy  Your turn: Write a balanced equation for the complete combustion of C 8 H 18.  Answer  2 C 3 H 18(l) + 25 O 2(g) --> 16 CO 2(g) + 18 H 2 O (g) + energy  Ex) Write a balanced equation for the complete combustion of C 3 H 8.  C 3 H 8(g) + O 2(g) --> CO 2(g) + H 2 O (g) + energy  C 3 H 8(g) + 5 O 2(g) --> 3 CO 2(g) + 4H 2 O (g) + energy  Your turn: Write a balanced equation for the complete combustion of C 8 H 18.  Answer  2 C 3 H 18(l) + 25 O 2(g) --> 16 CO 2(g) + 18 H 2 O (g) + energy