Starter 11/29  Write the balanced formula equation for: Lithium metal is added to a solution of aluminum sulfate to make aqueous lithium sulfate and aluminum metal.

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

Types of Chemical Reactions  5 basic types discussed here  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 where A forms a cation and X forms a anion

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

1. Synthesis  More difficult to predict:  calcium oxide and water CaO(s) + H 2 O(l)  Ca(OH) 2 (aq)  sulfur dioxide and water SO 2 (g) + H 2 O(l)  H 2 SO 3 (aq)  calcium oxide and sulfur dioxide CaO(s) + SO 2 (g)  CaSO 3 (s)

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

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) Ag 2 O(s)  Ag(s) + O 2 (s)  Water undergoes decomposition. H 2 O(l)  H 2 (g) + O 2 (g) 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)

2. Decomposition  More difficult to predict:  calcium carbonate CaCO 3 (s)  CaO(s) + CO 2 (g)  calcium hydroxide Ca(OH) 2 (s)  CaO(s) + H 2 O(l)  carbonic acid H 2 CO 3 (aq)  CO 2 (g) + H 2 O(l)

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 replaced: A + BX  B + AX OR anion replaced: Y + AX  X + AY

3. Single Replacement  Identify the “similar” element in the compound that it will replace  Find ions created  crossover to make new compound  zinc metal is added to solution of lead(II) nitrate Zn(s) + Pb(NO 3 ) 2 (aq)  Zn(NO 3 ) 2 (aq) + Pb(s) Zn(s) + Pb(NO 3 ) 2 (aq)  Zn(NO 3 ) 2 (aq) + Pb(s)  sodium iodide is added to chlorine gas NaI(aq) + Cl 2 (g)  NaCl(aq) + I 2 (s) NaI(aq) + Cl 2 (g)  NaCl(aq) + I 2 (s)

3. Single Replacement  zinc 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 similar elements switch places  2 compounds as reactants  2 compounds as products AX + BY  BX + AY

4. Double Replacement  identify which parts will switch places  find ions that will be created  crossover to create new compounds  silver nitrate and sodium chloride solutions are mixed AgNO 3 (aq) + NaCl(aq)  NaNO 3 (aq) + AgCl(s) AgNO 3 (aq) + NaCl(aq)  NaNO 3 (aq) + AgCl(s)  solutions of magnesium fluoride and potassium hydroxide are mixed MgF 2 (aq) + KOH(aq)  Mg(OH) 2 (aq) + KF(aq) MgF 2 (aq) + KOH(aq)  Mg(OH) 2 (aq) + KF(aq)

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  combines with oxygen  releases energy in form of heat/light  O 2 + compound as reactants  H 2 O (& usually CO 2 ) as products CH 4 + O 2  CO 2 + H 2 O

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