Chemical Reactions – Part IIFive Types of Chemical Reactions Unit 7: Stoichiometry - Part IV Mrs. Callender
Lesson Essential Question What are the five general types of chemical reactions?
Combination or Synthesis Two or more substances combine to form a new compound. A + X AX Fe(s) + S(s) FeS(s) Iron Wool added to Sulfur with heat yields Iron (II) Sulfide.
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. Aluminum(s) + Bromine(l) 2 Al(s) + 3 Br2(l) 2 AlBr3(S) Aluminum Bromide 3. Reactions of metals with sulfur. Silver(s) + Sulfur(s) Ag(s) + S(s) Ag2S(S) Silver Sulfide
Decomposition A single compound undergoes a reaction a produces two or more substances. A X A + X Potassium Chlorate is decomposed by heating forming potassium chloride and oxygen gas. KClO3(s) KCl(s) + O2(g)
Examples of Decomposition Reactions 1. Decomposition of Binary Compounds. 2 MgO(s) 2 Mg(s) + O2(g) Magnesium + Oxygen Magnesium Oxide(s) 2. Decomposition of Metal Carbonates. Decomposes into two separate elements. Aluminum Carbonate(s) Decomposes into metal oxide and CO2(g) 3. Decomposition of Metal Hydroxides (Bases) Al2(CO3)3(S) Al2O3(s) + 3 CO2(g) Aluminum Oxide + Carbon Dioxide 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
Examples of Decomposition Reactions 4. Decomposition of Metal Chlorates. 2 NaClO3(s) 2 NaCl(s) + 3 O2(g) sodium chloride + Oxygen Sodium Chlorate(s) 5. Decomposition of Ternary Acids. Decomposes to produce metal chloride and oxygen gas. Sulfuric Acid(l) H2SO4(l) SO3(g) + H2O(l) Sulfur Trioxide + Water Decomposes to produce Nonmetal Oxide (Acidic Anhydride) and water. Use this charge to form the acidic anhydride (nonmetal oxide) formula. Since the nonmetals in the ternary acid usually have multiple charges you must work backwards to find its charge. -2 3(-2) +6 4(-2) = +6 + X + +2 -8 2(+1) SO3 SO H2SO4
Lets try some examples… 4 2 1. Na(s) + O2(g) Na2O(s) SYNTHESIS 2. MgCO3(S) Decomposition MgO(s) + CO2(g) 3 2 2 FeBr3(s) 3. Fe(III)(s) + Br2(l) SYNTHESIS What’s wrong with the equation below? 2H3PO4(l) 2PO2(g) + 3 H2O(l) 2H3PO4(l) 2P2O5(g) + 3 H2O(l)
Single Replacement or Single Displacement One element displaces another element when higher on the activity chart. A + BX B + AX BX + Y B + YX Cu(s) + AgNO3(aq) Ag(s) + Cu(NO3)2(aq) Copper penny added to silver nitrate produces silver metal and blue aqueous copper (II) nitrate.
Examples of Single Displacement Reactions 1. Replacement of metal by another metal. Cu(II)(s) + 2AgNO3(aq) 2Ag(s) + Cu(NO3)2(aq) Silver + Copper (II) Nitrate Zn(s) + 2 HOH(l) Zn(OH)2(aq) + H2(g) Zinc Hydroxide + Hydrogen gas Copper(s) + Silver Nitrate(aq) 2. Replacement of hydrogen in water by a metal. Zinc(s) + Water(l) 3. Replacement of hydrogen in an acid by a metal. Magnesium(s) + Hydrochloric Acid(l) Mg(s) + 2 HCl(l) MgCl2(aq) + H2(g)
Examples of Single Displacement Reactions 4. Replacement of halogens by another halogen. Cl2(g) + 2 NaBr(s) Br2(l) + 2 NaCl(s) Bromine + SodiumChloride Chlorine(g) + Sodium Bromide(s)
Activity Series Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Lead Hydrogen Bismuth Copper Mercury Silver Platinum Gold 1. Metals can displace other metals provided that they are above the metal they are trying to displace. 2. Metals above hydrogen can displace hydrogen from an acid. 3. Metals from sodium upward can replace hydrogen from water.
Activity Series Fluorine Chlorine Bromine Iodine 1. Halogens can replace other halogens provided they are higher than the halogen they are trying to replace. 2 NaCl(s) + F2(g) 2 NaF(s) + Cl2(g) NaF(s) + Cl2(g) No Reaction
DoubleReplacement 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. Pb(NO3)2(aq) + KI(aq) PbI2(s) + KNO3(aq) Lead (II) Nitrate added to Potassium Iodide produces a Lead (II) Iodide ppt. and aqueous Potassium Nitrate solution.
Examples of Double Displacement Reactions 1. Copper (II)Sulfate(aq)+Lead (II)Nitrate(aq) 2. Zn(OH)2(aq) +2 NaBr(aq) ZnBr2(aq) + 2NaOH(aq) Zinc Bromide + Sodium Hydroxide 1. CuSO4( (II)aq) + Pb(NO3)2(aq) PbSO4(s) + Cu(NO3)2(aq) Lead(II) Sulfate + Copper (II) Nitrate Precipitate 2. Zinc Hydroxide(aq) + Sodium Bromide(aq)
Combustion Reactions A substance combines with oxygen producing a large amount of energy in the form of heat or light. Reactive elements combine with oxygen. P4(s)+ 5 O2(g)P4O10(s) This is also a synthesis reaction. C3H8(g) + 5 O2(g) 3CO2(g)+ 4 H2O(l) + Energy The burning of organic materials in general.