Chemical Reactions

5 Types of Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion

Synthesis A + B  AB 4Fe + 3O2  2Fe2O3 Two or more reactants combine to form a single product. (Only 1 product forms) A + B  AB 4Fe + 3O2  2Fe2O3

Decomposition AB  A + B 2H2O  2H2 + O2 A single reactant forms two or more products. (Only 1 reactant) AB  A + B 2H2O  2H2 + O2

Single Replacement “Cutting In” One element takes the place of another element in a compound. A + BC  AC+ B metal replaces metal (+), nonmetal replaces nonmetal (-) Fe + CuSO4 FeSO4 + Cu Cl2 + 2NaBr  2NaCl + Br2

Double Replacement “Switching Partners” Ions of two compounds switch places. AB + CD  AD + CB Pb(NO3)2 + 2KI  PbI2 + 2KNO3

Combustion Reaction Uses oxygen (O2) as a reactant. Produced Heat. The products usually include CO2 and H2O CH3OH + O2  CO2 + H2O

Check for Understanding What do you look for in a synthesis reaction? Answer: Two or more reactants and one product. What do you look for in a decomposition reaction? Answer: One reactant and two or more products. 4/26/2019

Check for Understanding What do you look for in a combustion reaction? Answer: Two products: CO2 and H2O. What do you look for in a single replacement reaction? Answer: One element takes the place of another element in a compound. 4/26/2019

Check for Understanding What do you look for in a double replacement reaction? Answer: Two ionic compounds exchange ions to form two new ionic compounds. 4/26/2019

Check for Understanding Classify each reaction: 2C6H6 + 15O2  12CO2 + 6H2O Answer: Combustion N2 + 3H2  2NH3 Answer: Synthesis F2 + MgCl2  MgF2 + Cl2 Answer: Single Displacement (NH4)2Cr2O7  N2 + 4H2O + Cr2O3 Answer: Decomposition KCl + AgNO3  AgCl + KNO3 Answer: Double Displacement 4/26/2019

Review

4 Indicators of Chemical Reactions How do you know a chemical reaction when you see one? A Gas is Created (NOT a phase change) Release/Absorption of Energy (heat or light) Extreme Color Change Formation of a Precipitate (solid)

Release/Absorption of Energy Exothermic – energy is released Feels HOT to the touch. ex. Burning wood, fireworks exploding, Freezing Endothermic – energy is absorbed Feels COLD to the touch. Ice packs, Melting

Balancing Equations Law of Conservation of Mass: No atoms are created or destroyed in chemical reactions. Atoms are just rearranged. Reactants  Products #atoms of each element in the reactants = # atoms of each element in the products

Balancing Equations Rules:n NEVER change the subscripts. Add coefficients to balance the number of atoms. Save O and H for last. If you have an odd number of an element (ex. oxygen) on one side, try putting a 2 (or another even coefficient).

Name the reaction type and Balance the equation __ Ca3(PO4)2 + __ H2SO4  __ CaSO4 + __H3PO4 ___KClO3  ___KCl + ___O2 ___C2H2 + ___O2  ___CO2 + ___H2O ___C + ___H2O  ___CO + ___H2 ___P4 + ___O2  ___P2O5

Name the reaction type and Balance the equation __ Ca3(PO4)2 + __ H2SO4  __ CaSO4 + __H3PO4

Name the reaction type and Balance the equation ___KClO3  ___KCl + ___O2

Name the reaction type and Balance the equation ___C2H2 + ___O2  ___CO2 + ___H2O

Name the reaction type and Balance the equation ___C + ___H2O  ___CO + ___H2

Name the reaction type and Balance the equation ___P4 + ___O2  ___P2O5