Chemical Reactions Five Types of Chemical Reactions Simplified for Introduction

Lesson Essential Question What are the general types of chemical reactions?

Combination or Synthesis Two or more substances combine to form a new compound. A + X AX Iron Wool added to Sulfur with heat yields Iron (II) Sulfide. Fe(s) + S(s) FeS(s)

Iron + Sulfur

Examples of Synthesis Reactions 1. Reactions of metals with oxygen. Magnesium(s) + Oxygen(g) 2 Mg(s) + O2(g) 2 MgO(S) Magnesium Oxide 2. Reactions of metals with halogens. 2 Al(s) + 3 Br2(l) 2 AlBr3(S) Aluminum Bromide Aluminum(s) + Bromine(l) 3. Reactions of metals with sulfur. Silver(s) + Sulfur(s) Ag(s) + S(s) Ag2S(S) Silver Sulfide

Decomposition A X A + X KClO3(s) KCl(s) + O2(g) A single compound undergoes a reaction and produces two or more substances. A X A + X KClO3(s) KCl(s) + O2(g) Potassium Chlorate is decomposed by heating forming potassium chloride and oxygen gas.

Examples of Decomposition Reactions 1. Decomposition of Binary Compounds. Magnesium Oxide(s) 2 MgO(s) 2 Mg(s) + O2(g) Magnesium + Oxygen 2. Decomposition of Metal Carbonates. Decomposes into two separate elements. Aluminum Carbonate(s) Al2(CO3)3(S) Al2O3(s) + 3 CO2(g) Aluminum Oxide + Carbon Dioxide Decomposes into metal oxide and CO2(g) 3. Decomposition of Metal Hydroxides (Bases) Magnesium Hydroxide(s) Mg(OH)2(s) MgO(S) + H2O(g) Magnesium Oxide(s) +Water Vapor(g) Decomposes into metal oxide (basic anhydride) and H2O

Single Replacement or Single Displacement One element displaces another element when higher on the activity chart. A + BX B + AX BX + Y B + YX Copper penny added to silver nitrate produces silver metal and blue aqueous copper (II) nitrate. Cu(s) + AgNO3(aq) Ag(s) + Cu(NO3)2(aq)

Double Replacement or Double Displacement The ions of two compounds switch places in an aqueous solution to form two new compounds. AY + BX BY + AX One of the products is usually an insoluble gas that bubbles out of the solution, a precipitate, or a molecular compound, usually water. Lead (II) Nitrate added to Potassium Iodide produces a Lead (II) Iodide ppt. and aqueous Potassium Nitrate solution. Pb(NO3)2(aq) + KI(aq) PbI2(s) + KNO3(aq)

Examples of Double Displacement Reactions 1. Copper (II)Sulfate(aq) + Lead (II) Nitrate(aq) 1. CuSO4( (II)aq) + Pb(NO3)2(aq) PbSO4(s) + Cu(NO3)2(aq) Lead (II) Sulfate + Copper (II) Nitrate Precipitate 2. Zn(OH)2(aq) +2 NaBr(aq) ZnBr2(aq) + 2NaOH(aq) Zinc Bromide + Sodium Hydroxide 2. Zinc Hydroxide(aq) + Sodium Bromide(aq)

Combustion Reactions C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(l) + Energy A substance combines with oxygen producing a large amount of energy in the form of heat or light. The burning of organic materials in general. C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(l) + Energy