Ch. 8 Chemical Equations and Reactions 8.2a Types of Chemical Reactions

Types of Chemical Reactions  5 basic types not all reactions fall in these categories not all reactions fall in these categories  you should be able to: categorize a reaction by its reactant(s) categorize a reaction by its reactant(s) predict the product(s) predict the product(s)

1. Synthesis  also called composition reaction  combining more than one reactant  to make only one product A + X  AX A forms a cation (metal) and X forms a anion (Non-metal)

1. Synthesis  find ion created by each reactant  Criss cross to write formula for product  barium metal is reacted with solid sulfur.  Ba(s) + S 8 (s)  BaS(s)  magnesium metal reacts with bromine  Mg(s) + Br 2 (l)  MgBr 2 (s)

1. Synthesis  Rubidium metal and solid sulfur Rb(s) + S 8 (s)  Rb 2 S(s)  Magnesium ribbon and oxygen gas Mg(s) + O 2 (g)  MgO(s)  Solid Sodium and chlorine gas Na(s) + Cl 2 (g)  NaCl(s)  Magnesium ribbon and fluorine gas Mg(s) + F 2 (g)  MgF 2 (s)

2. Decomposition  opposite of synthesis  usually require energy  breaking apart one reactant  to make more than one product AX  A + X A is a cation and X is a anion

2. Decomposition  Find elements that will be created  Write them in natural state  Solid silver oxide is heated.  Ag 2 O(s)  Ag(s) + O 2 (s)  Water undergoes decomposition.  H 2 O(l)  H 2 (g) + O 2 (g)

2. Decomposition  liquid water H 2 O(l)  H 2 (g) + O 2 (g)  Solid lithium nitride Li 3 N(s)  Li(s) + N 2 (g)  solid aluminum sulfide Al 2 S 3 (s)  Al(s) + S 8 (s)

3. Single Replacement  an element replaces a similar element in a compound  1 element & 1 compound as reactants  1 element & 1 compound as products Cation (metal) replaced: A + BX  B + AX OR anion (nonmetal) replaced: Y + AX  X + AY

3. Single Replacement  Identify the “similar” element in the compound that it will replace 1. Determine the ion charges of all elements or polyatomic ions present 2. Switch “like” charges 3. crossover to make new compound

3. Single Replacement  zinc (II) and hydrochloric acid Zn(s) + HCl(aq)  ZnCl 2 (aq)  iron and water Fe(s) + H 2 O(l)  FeO(aq)  magnesium and lead (II) nitrate Mg(s) + Pb(NO 3 ) 2 (aq)  Mg(NO 3 ) 3 (aq) + Pb  chlorine and potassium bromide Cl 2 (g) + KBr(s)  KCl(s) + Br 2 (g)

4. Double Replacement  two similarly charged elements switch places  2 compounds as reactants  2 compounds as products AX + BY  BX + AY Cations (Metals) switch with each other

4. Double Replacement 1. Identify the cations that will switch places 2. find ions that will be created 3. crossover to create new compounds

4. Double Replacement  barium chloride and sodium sulfate BaCl 2 (aq) + Na 2 SO 4 (aq)  NaCl(aq) + BaSO 4 (s)  iron sulfide and hydrochloric acid FeS(aq) + HCl(aq)  FeCl 2 (aq) + H 2 S(g)  hydrochloric acid and sodium hydroxide HCl(aq) + NaOH  NaCl(aq) + H 2 O(l)  potassium iodide and lead (II) nitrate KI(aq) + Pb(NO 3 ) 2  KNO 3 (aq) + PbI 2 (s)

5. Combustion  ALWAYS combines with oxygen, O 2  releases energy in form of heat/light  Reactants: Compound (containing H and/or C) + O 2  Products: H 2 O (& usually CO 2 ) Reactants  Products CH 4 + O 2  CO 2 + H 2 O

5. Combustion  always makes H 2 O and/or CO 2  Choose products based on what elements exist in reactants  solid carbon reacts with oxygen  C(s) + O 2 (g)  CO 2 (g)  C 2 H 5 OH reacts with oxygen in air.  C 2 H 5 OH + O 2 (g)  CO 2 (g) + H 2 O(l)

Combustion  hydrogen and oxygen H 2 (g) + O 2 (g)  H 2 O(g)  propane (C 3 H 8 ) and oxygen C 3 H 8 (g) + O 2 (g)  CO 2 (g) + H 2 O(g)

Practice Classify each of the following reactions one of the five basic types and predict the products when appropriate.  Na 2 O + H 2 O  NaOH synthesis synthesis  zinc metal reacts with hydrochloric acid: Zn (s) + 2HCl(aq)  ZnCl 2 (aq) + H 2 (g) Zn (s) + 2HCl(aq)  ZnCl 2 (aq) + H 2 (g) single replacement single replacement  Ca(s) + 2H 2 O(l)  Ca(OH) 2 (aq) + H 2 (g) single replacement single replacement

Practice  2H 2 O 2 (aq)  O 2 (g) + 2H 2 O(l) decomposition decomposition  copper pieces react with solution of silver nitrate Cu(s) + 2AgNO 3 (aq)  2Ag(s) +Cu(NO 3 ) 2 (aq) Cu(s) + 2AgNO 3 (aq)  2Ag(s) +Cu(NO 3 ) 2 (aq) single replacement single replacement  gaseous ethene (C 2 H 4 ) reacts with oxygen gas C 2 H 4 (g) + O 2 (g)  CO 2 (g) + H 2 O(g) C 2 H 4 (g) + O 2 (g)  CO 2 (g) + H 2 O(g) combustion combustion  solid zinc oxide reacts with solid lithium ZnO(s) + Li(s)  2Zn(s) + Li 2 O(g) ZnO(s) + Li(s)  2Zn(s) + Li 2 O(g) single replacement single replacement

Practice  Na 2 O(s) + 2CO 2 (g) + H 2 O(l)  NaHCO 3 (s) synthesis synthesis  Ca(s) + H 2 O(l)  Ca(OH) 2 (aq) + H 2 (g) single replacement single replacement  KClO 3 (s)  KCl(s) + O 2 (g) decomposition decomposition  sulfuric acid reacts with a solution of barium choride H 2 SO 4 (aq) + BaCl 2 (aq)  HCl(aq) + BaSO 4 (s) H 2 SO 4 (aq) + BaCl 2 (aq)  HCl(aq) + BaSO 4 (s) double replacement double replacement