Chemical Reactions • Chemical reactions are grouped according to patterns in the chemical formulas.
Synthesis Reactions • Two reactants combine to make a larger or more complex product.
Synthesis Reactions An example of a synthesis reaction is: 4 Al(s) + 3 O2(g) 2 Al2O3(s)
Decomposition Reactions • Large compounds are broken down into smaller compounds or elements.
Single Displacement Reactions • One element displaces another element in a compound, producing a new compound and a new element. A + BC → AC + B
Single Displacement Reactions • In reactions with ionic compounds and metals, the positive ion (cation) is replaced. Copper + silver nitrate → copper (II) nitrate + silver Cu(s) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 Ag
Single Displacement Reactions • Metals rarely occur naturally as pure elements → ….single displacements often purify metals in order to use them.
Double Displacement Reactions • Two elements in different compounds trade places. • Two solutions that undergo a double displacement reaction produce an insoluble compound called a precipitate.
Double Displacement Reactions AB + CD → AD + BC
An example of a double displacement reaction is Pb(NO3)2(aq) + 2 KI(aq) PbI2(s) + 2 KNO3(aq) • Word Equation?
Word Equation? Pb(NO3)2(aq) + 2 KI(aq) PbI2(s) + 2 KNO3(aq) • Lead (II) nitrate + potassium iodide Lead (II) Iodide + Potassium nitrate
Pb(NO3)2(aq) + 2 KI(aq) PbI2(s) + 2 KNO3(aq) • Precipitate?
Pb(NO3)2(aq) + 2 KI(aq) PbI2(s) + 2 KNO3(aq) • Precipitate • lead (II) iodide, PbI2 • appears as a bright yellow insoluble solid.
Vocabulary Synthesis Reaction Decomposition Reaction Single Displacement Reaction Double Displacement Reaction Precipitate
Homework Pg. 243 # 1, 3 – 5 Course Package Pg. 22, 23
Combustion • A chemical reaction in which the fuel reacts with oxygen • Commonly known as burning • Usually results in an oxide and energy (the flame) • Oxygen is known as an oxidizer
Complete Combustion of Hydrocarbons • If there is enough oxygen, all materials are burned completely Hydrocarbon + oxygen -> carbon dioxide + water + energy CxHy (g) + O2 (g)-> CO2(g) + H2O (g) + energy
Incomplete Combustion of Hydrocarbons • If there is NOT enough oxygen, all materials are NOT burned completely Hydrocarbon + oxygen -> carbon dioxide + water + carbon monoxide + carbon + energy CxHy (g) + O2 (g)-> CO2(g) + H2O (g) + CO(g) + C (s) + energy Creates carbon monoxide and soot
Carbon Monoxide (CO) • Odourless, colourless gas • Highly toxic • Carbon dioxide poisoning symptoms are nausea, headache, dizziness and respiratory problems • Maintain your furnace regularly and don’t leave your car running in your garage
Soot • Particles of Carbon
Combusting Elements • Element + Oxygen -> Element Oxide + Energy • Hydrogen • 2H2(g) + O2(g) -> 2H2O(g) + energy • Magnesium • 2Mg(s) + O2 -> 2MgO + energy
Test for Hydrogen • If Hydrogen is exposed to a flame it reacts and produces energy in the form of a “POP” • Produces water
Test for Oxygen • In Oxygen, a flame is encouraged • If a glowing splint enters a test tube of oxygen, it relights
Test for Carbon Dioxide • Carbon dioxide smothers a flame • If a flaming splint is exposed to carbon dioxide, the flame extinguishes
Types of Reactions • Pg 243 # 2-4, 8 • Combustion • Pg 251 # 2,3,5,6 • Read Corrosion – Pg 252-254 • Make point form notes