6.1: Types of Chemical Reactions Movie: types of chemical reactions: http://www.youtube.com/watch?v=i-HHvx1VC_8

Learning Outcomes Identify, give evidence for, predict products of, and classify the following types of chemical reactions: 1. Synthesis (combination) 2. Decomposition 3. Single Replacement 4. Double Replacement 5. Neutralization (acid/base) 6. Combustion

Vocabulary Synthesis Decomposition Neutralization Single displacement Double displacement Combustion

Chemical Reactions A chemical change: any change in which a new substance is formed. Evidence of a Chemical Change: Release of energy as heat Release of energy as light Change in colour Formation of a gas Change in odour…

Types of Chemical Reactions Neutralization: Acid(H) + Base(OH)  salt + H(OH) Combustion: AB + oxygen  CO2 + H2O Synthesis: A + B  AB Decomposition: AB  A + B Single displacement: A + BC  AC + B Double displacement: AB + CD  AD + CB

Synthesis Reactions A + B  AB where A and B represent elements Synthesis reactions are also known as FORMATION reactions. Two or more reactants (usually elements) join to form a compound. A + B  AB where A and B represent elements The elements may form ionic compounds, like… Sodium metal and chlorine gas combine to form sodium chloride. 2Na + Cl2  2NaCl Sodium added to chlorine gas See pages 258 - 259 (c) McGraw Hill Ryerson 2007

Synthesis Reactions

Types: Synthesis General: A + B  AB Example C + O2  + O O O O O O O

SYNTHESIS REACTION (iron + sulphur): Synthesis Reactions OTHER EXAMPLES… Elements that form ionic compounds: Magnesium metal reacts with oxygen gas to form magnesium oxide. 2Mg + O2  2MgO 2. Elements that form covalent compounds: Nitrogen gas and oxygen gas join to form dinitrogen monoxide. 2N2 + O2  2N2O SYNTHESIS REACTION (iron + sulphur): http://www.youtube.com/watch?v=A5H6DVe5FAI See pages 258 - 259 (c) McGraw Hill Ryerson 2007

Decomposition Reactions Decomposition reactions are the opposite of synthesis reactions. A compounds breaks down into two or more products (often elements). AB  A + B where A and B represent elements 1. Ionic compounds may decompose to produce elements, like the following: Table salt, sodium chloride, can be broken down into sodium metal and chlorine gas by melting salt at 800ºC and running electricity through it. 2NaCl  2Na + Cl2 See page 260 (c) McGraw Hill Ryerson 2007

Decomposition Reactions See page 260 (c) McGraw Hill Ryerson 2007

Types: Decomposition Example: NaCl  Cl Na Cl + Na General: AB  A + B

Types: Decomposition Example 2HgO  O Hg Hg O + General: AB  A + B

Decomposition Reactions 2. Covalent compounds may decompose into elements, like the following: By running electricity through water, the water molecules decompose into hydrogen and oxygen gases. 2H2O  2H2 + O2 DECOMPOSITION REACTION: http://www.youtube.com/watch?v=NddwtXEA_Ak See page 260 (c) McGraw Hill Ryerson 2007

Single Replacement Reactions Single replacement reactions replace one element from a compound with another element. A compound and an element react, and the element switches places with part of the original compound. A + BC  B + AC where A is a metal, or A + BC  C + BA where A is a non-metal See page 261 (c) McGraw Hill Ryerson 2007

Single Replacement Reactions

Types: Single displacement Example: Zn + CuCl2  Zn Cl Cu + Cl Zn Cu + General: AB + C  AC + B

Single Replacement Reactions 1. When A is a metal: Aluminum foil in a solution of copper(II) chloride produces solid copper and aluminum chloride. 2Al + 3CuCl2  3Cu + 2AlCl3 2. When A is a non-metal: When fluorine is bubbled through a sodium iodide solution, iodine and sodium fluoride are produced. Fl2 + 2NaI  I2 + 2NaF SINGLE REPLACEMENT: http://www.youtube.com/watch?v=hKtynbVtMKc

Double Replacement Reactions Double replacement reactions swap elements between 2 compounds that react together to form two new compounds. Two compounds react, with elements switching places between the original compounds. AB + CD  AD + CB See page 262 (c) McGraw Hill Ryerson 2007

Double Replacement Reactions See page 262 (c) McGraw Hill Ryerson 2007

Types: Double displacement Example: MgO + CaS S O  Mg Ca + O S Mg Ca + General: AB + CD  AD + CB

Double Replacement Reactions Two solutions react to form a precipitate (solid) and another solution. Ionic solution + ionic solution  ionic solution + ionic solid. AB + CD  AD + CB When potassium chromate and silver nitrate react, they form a red precipitate, silver chromate, in a solution of potassium nitrate. K2CrO4 + 2AgNO3  Ag2CrO4 + 2KNO3 silver chromate DOUBLE REPLACEMENT: http://www.youtube.com/watch?v=opY3FLrPTa4 (c) McGraw Hill Ryerson 2007

Neutralization Reactions Neutralization reactions occur when an acid (most compounds starting with H) and a base (most compounds ending in OH) react to form a salt and water. Neutralization reactions are a type of double replacement. Acid + base  salt + water HX + MOH  MX + H2O where X and M are elements See page 263 (c) McGraw Hill Ryerson 2007

Neutralization Reactions 1. Sulfuric acid is used to neutralize calcium hydroxide: H2SO4 + Ca(OH) 2  CaSO4 + 2H2O 2. Phosphoric acid helps to neutralize the compounds that cause rust, such as iron(II) hydroxide. H3PO4 + 3Fe(OH)2  Fe3(PO4)2 + 6H2O NEUTRALIZATION: http://www.youtube.com/watch?v=_P5hGzA6Vb0 See page 263 (c) McGraw Hill Ryerson 2007

where X and Y represent integers Combustion Reactions Combustion reactions occur when a compound or element react with oxygen to release energy and produce an oxide. Also sometimes referred to as hydrocarbon combustion. CXHY + O2  CO2 + H2O where X and Y represent integers METHANOL + oxygen: http://www.youtube.com/watch?v=98JuJ-G1qXY&feature=related See page 264 (c) McGraw Hill Ryerson 2007

Combustion Reactions 1. Natural gas (methane) is burned in furnaces to heat homes. CH4 + O2  CO2 + 2H2O + energy 2. An acetylene torch is used to weld metals together. 2C2H2 + 5O2  4CO2 + 2H2O + energy 3. Carbohydrates like glucose combine with oxygen in our body to release energy. C6H12O6 + 6O2  6CO2 + 6H2O + energy Acetylene torch See page 264 (c) McGraw Hill Ryerson 2007

SUMMARY OF REACTIONS Take the Section 6.1 Quiz MOVIE TO REVIEW: http://www.bcscience.com/bc10/pgs/videos_013_chemical_reactions.html See page 265 (c) McGraw Hill Ryerson 2007 Take the Section 6.1 Quiz