Lesson #6: Chemical Types
Type #1 The Synthesis In this type of reaction 2 or more elements or compounds combine to form a more complex compound Two or more things become one bigger thing (ex) 2Mg + O 2 2MgO A Synthesis reaction can be illustrated using the general equation: A + B AB 2 or more elements or compounds more complex compound
Type #2 The Decomposition During this type of reaction, one compound splits into 2 or more simpler compounds or elements Something is broken down (ex) 2HgO 2Hg + O 2 A Decomposition reaction can be illustrated using the general equation: AB A + B Compound 2 or more elements or simpler compounds
Type #3 The Single Displacement In this type of reaction, one element replaces another element in an ionic compound Single displacement reactions can be illustrated using the general equation: element + compound element + compound A + BC B + AC An Element and a Compound react to form TWO new products There are 2 possible single displacement reactions: 1.One Positive Ion replaces another: Zn + 2HCl ZnCl 2 + H 2 - Note that Zinc and Hydrogen are both positive ions - ALSO: Note that H 2 is a diatomic molecule. Treat a diatomic molecule as an element 2.One Negative Ion replaces another: Cl 2 + 2NaBr 2NaCl + Br 2 - Note: Chlorine and Bromine are both negative ions
Type #4 The Double Displacement In this reaction type, 2 ionic compounds split up and exchange ion partners (ex) FeS + 2HCl FeCl 2 + H 2 S A Double displacement reaction can be illustrated using the general equation: AC + BD AD + BC compound + compound compound + compound Two Ionic Compounds react to form two different Ionic Compounds
Type #5 The Combustion This is a reaction involving Oxygen and a Hydrocarbon (a compound composed of Carbon and Hydrogen) (ex) CH 4 + O 2 CO 2 + H 2 O Note: ALL Hydrocarbons combine with oxygen to form Water and Carbon Dioxide A Combustion can be written using the general equation: C x H y + O 2 CO 2 + H 2 O Any Hydrocarbon + Oxygen Carbon Dioxide + Water
Incomplete Combustion This is a combustion reaction in which there is not enough Oxygen present for the Hydrocarbon to be consumed cleanly. As a result Carbon Monoxide is produced in addition to the Carbon Dioxide and Water C x H y + Insufficient O 2 CO + CO 2 + H 2 0 Biological Combustion (Cellular Respiration) Carbohydrates are a special type of hydrocarbon Cellular respiration is considered a Combustion C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 0 + Energy
What are some different forms of Energy? The Law of Conservation of Energy This law states that energy can be transformed from one form to another but it cannot be created or destroyed in a chemical reaction All chemical reactions involve the release or absorption of energy Energy is required to break bonds and Energy is released when bonds are formed
Exothermic s These are energy releasing reactions In these types of reactions, more bonds are being formed than are being broken so more energy is being released than is being absorbed If Energy is a Product of a reaction the reaction is Exothermic Generally, Synthesis and Combustion s are Exothermic s Endothermic s These are energy absorbing reactions In these reaction types, more bonds are being broken than are being formed so more energy is being absorbed than is being released If Energy is a Reactant in the reaction the reaction is Endothermic Generally, Decomposition s are Endothermic