6.1 - Types of Chemical Reactions 6 Types of Chemical Rxns. 1.Synthesis / Combination 2.Decomposition 3.Single Replacement 4.Double Replacement 5.(Acid-Base) Neutralization 6.Combustion By examining the reactants, you can classify a reaction, then predict the identity of the products.

1. Synthesis Reactions to synthesize means to make something! ≥ 2 reactants (usually elements) combine to form a single product In general: A + B  AB (element) + (element)  (compound)

1. Synthesis Reactions 1.The elements may form ionic compounds, for example… a) sodium metal and chlorine gas combine to form_____________ Rxn: b) magnesium metal reacts with oxygen gas to form _____________ Rxn:

1. Synthesis Reactions FYI… in a synthesis reaction between a metal and a non-metal, e -s are transferred from the metal to the non-metal, producing ions  it is easy to predict the product when multivalent metals / covalent compounds are involved, it is more difficult to predict the product

1. Synthesis Reactions 2. or the elements may form covalent compounds, for example:  nitrogen gas and oxygen gas join to form _______________________ Rxn: Do “Practice Problems” on p. 259.

2. Decomposition Reactions A decomposition reaction is the reverse of a synthesis reaction it breaks down a compound into… a)smaller compounds ex. H 2 CO 3  b) separate elements ex. H 2 O  In general: AB  A + B

2. Decomposition of… …an ionic compound: table salt can be decomposed by melting it at 800ºC and passing an electric current through it: ex.2NaCl  2Na + Cl 2 …a covalent compound: electrolysis of (passing an electric current through) water yields hydrogen and oxygen gases in a decomposition rxn.: ex. 2H 2 O  2H 2 + O 2 Do “Practice Problems” on p. 260.

3. Single Replacement Reactions In a single replacement reaction, a reactive element (could be a metal or a non-metal) and a compound react to produce… another element, and another compound. element + compound  different + different element compound

3. Single Replacement Reactions Metal Element + Compound A + BC  B + AC (where A is a metal) ex. Al + CuCl 2   electrons transfer from Al atoms to Cu 2+ ions  Cu atoms and Al 3+ ions are released  Al 3+ ions combine with Cl 1- ions to form a compound

3. Single Replacement Reactions Non-metal Element + Compound the non-metal replaces the other non-metal A + BC  C + BA (where A is a non-metal) ex.F 2 + NaI  Do “Practice Problems” on p. 261.

4. Double Replacement Reactions Double replacement reactions generally involve 2 ionic solutions reacting to form 2 other ionic compounds.  one of the products is a precipitate (an insoluble solid that forms in a solution)  the other product may form a precipitate, or remain in solution In general: AB (aq) + CD (aq)  AD (aq) + CB (s) (ionic sol’n) + (ionic sol’n)  (ionic sol’n) + (ionic solid)

4. Double Replacement Reaction Write a balanced equation for each rxn. 1.When potassium chromate and silver nitrate react, they form silver chromate (a red precipitate) in a solution of potassium nitrate.

4. Double Replacement Reaction Write a balanced equation for each rxn. 2.When sodium hydroxide solution is combined with iron (III) chloride, a precipitate is formed involving the iron (III) ion.

5. Neutralization / Acid-Base Reactions A neutralization reaction occurs when an acid and a base react to form a salt and water. Recall:  acid – formula likely to have H on the left  base – formula with a metal or NH 4 + on the left, and OH - on the right In general: acid + base  salt + water HX + MOH  MX + H 2 O  X represents a –ve ion  M represents a +ve ion

5. Neutralization / Acid-Base Reactions Write a balanced equation for each rxn. 1.Sulphuric acid is used to neutralize calcium hydroxide. 1.Phosphoric acid helps to neutralize iron (II) hydroxide, one of the compounds that causes rust.

6. Combustion Reactions Combustion is the rapid reaction of a compound or element with oxygen to produce an oxide and to release energy.

6. Combustion Reactions hydrocarbon + oxygen  carbon dioxide + dihydrogen monoxide  sometimes referred to as hydrocarbon combustion  C X H Y + O 2  CO 2 + H 2 O + energy  (X and Y represent natural numbers) carbohydrate + oxygen  carbon dioxide + dihydrogen monoxide  Carbohydrates (ie. glucose) combine with oxygen in our bodies to release energy via a process called…  ex. C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy

6. Combustion Reactions Write a balanced equation for each rxn. 1.Methane (natural gas) is burned in furnaces in the presence of oxygen gas to heat homes. 1.An acetylene (C 2 H 2 ) torch is used to weld metal.

Summary of Types of Chemical Reactions Take the Section 6.1 Quiz

Practice Problems – Classify the reaction type & write a balanced equation. 1.Fe 2 O 3 →

Practice Problems – Classify the reaction type & write a balanced equation. 2.Al + NiBr 3 →

Practice Problems – Classify the reaction type & write a balanced equation. 3.Cl 2 + NiBr 2 →

Practice Problems – Classify the reaction type & write a balanced equation. 4.HCl + Mg(OH) 2 →

Practice Problems – Classify the reaction type & write a balanced equation. 5.C 18 H 38 + O 2 →

Practice Problems – Classify the reaction type & write a balanced equation. 6.Li + N 2 →

Practice Problems – Classify the reaction type & write a balanced equation. 7.Pb(NO 3 ) 2 + NaI →

1. Classify the following chemical reactions and balance each equation. a) Fe (s) + O 2 (g) → FeO (s) b) Fe (s) + CuS0 4 (aq) → FeSO 4 (aq) + Cu (s) c) Cr (s) + SnCl 4 (aq) → CrCl 3 (aq) + Sn (s) d) H (l) → H 2 O (l) + O 2 (g) e) Ca(OH) 2 (s) + HCl (l) → CaCl 2 + HOH (l)

1. Classify the following chemical reactions and balance each equation. a) 2Fe (s) + O 2 (g) → 2FeO (s) b) Fe (s) + CuS0 4 (aq) → FeSO 4 (aq) + Cu (s) c) 4Cr (s) + 3SnCl 4 (aq) → 4CrCl 3 (aq) + 3Sn (s) d) 2H (l) → 2H 2 O (l) + O 2 (g) e) Ca(OH) 2 (s) + 2HCl (l) → CaCl 2 + 2H 2 O (l)

2. Classify the reaction type & write a balanced equation. a) FeS (s) + HCl (l) → b) NaOH (s) + H 2 SO 4 (l) → c) Ag (s) + S 8 (s) → d) Fe 2 O 3 (s) → e) Hg (l) + H 2 SO 4 (l) →

2. Classify the reaction type & write a balanced equation. a) FeS (s) + 2HCl (l) → FeCl 2 (s) + H 2 S (g) b) 2NaOH (s) + H 2 SO 4 (l) → 2H 2 O(l) + Na 2 SO 4 (s) c) 16Ag (s) + S 8 (s) → 8Ag 2 S (s) d) 2Fe 2 O 3 (s) → 4Fe (s) + 3O 2 (g) e) Hg (l) + H 2 SO 4 (l) → HgSO 4 (s) + H 2 (g)