Predicting Reactions Predicting Reactions

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Predicting Reactions Predicting Reactions Powered By Docstoc
					Predicting Reactions
         Presented by
       Mr. Mark Langella
    AP Chemistry Instructor
   College Board Consultant
  Why do the reactions occur?
 GibbsFree Energy drives the
  Spontaneous reactions
     Lower PE energy
     Formation of Stronger Bonds
     Greater Entropy ( Formation of Gases)
 Solubility
 Formation    Constant
        Ways of Expressing
 Word  equation
 In word equations, the names of the
  reactants and products are written out.
  The following example is a word equation:
 carbon + oxygen carbon dioxide
         Formula equations

 Formula  equations consist of formulas
  substituted for the names in the word
  equation. The reaction above becomes
 C + O2     CO2
               Ionic equations

   In ionic equations, all water soluble compounds
    in an aqueous solution are separated into ions.
   2NaI(aq) + Pb(NO3)2(aq)           2NaNO3(aq) + PbI2(s)
   2Na+(aq) + 2I-(aq) + Pb2+(aq) + 2NO3-(aq) 2Na+(aq) + 2NO3-(aq) +

   Spectator ions - Spectator ions do not participate in the
    chemical reaction. That is, they are identical on both
    sides of the equation.
               Net ionic equations

 The    net ionic equation contains all of the
    particles in the ionic equation less any
    spectator ions.
 2Na+(aq) + 2I-(aq) + Pb2+(aq) + 2NO3-(aq)   2Na+(aq) + 2NO3-(aq) +
 Pb2+(aq) + 2I-(aq)       PbI2(s)
 We were reminded (especially by the
  combustion reaction above) that the coefficients
  used for balancing should be the lowest possible
  WHOLE NUMBER coefficients.
 All other rules for the balanced equations are the
  same - omit spectator ions, assume a reaction
  occurs, write the formulas for molecular
  compounds (e.g. HF) as undissociated species
  in solution, etc.
       Synthesis or Combination
 In synthesis or combination reactions, two
  or more substances combine together to
  form a single product.
 The general form is A + B      C
 The products must contain only those
  elements found in the reactants.
     Metal + Nonmetal              Salt
 Magnesium   ribbon is burned in oxygen

A strip of magnesium metal is heated
 strongly in pure nitrogen gas
                    Online Demos
   Reaction of Magnesium and Oxygen
   Reaction of Iron and Sulfur
   Reaction of Potassium and Oxygen
   Reaction of Lithium and Oxygen
   Reaction of Lithium and Chlorine
   Reaction of Sodium and Oxygen
   Reaction of Zinc and Sulfur
Nonmetal + Nonmetal Molecular
 PureSolid Phosphorus (White Form) is
 burned in air

 Reaction   of Phosphorus and Chlorine
     Website:
Reaction of Hydrogen and
 Preparation   of the Group 1 hydrides
 These are made by passing hydrogen gas
  over the heated metal. For example, for
  lithium hydride:
 2Li (s) + H2(g)     2LiH
Nonmetal Oxide + Water             Oxyacid
 Oxy  Acid= Contains H+ ions attached to
  common Polyatomic ion of Nonmetal
  Oxide plus one more oxygen
 Solid dinitrogen pentoxide is added to
 Sulfur trioxide gas is bubbled into water
     Nonmetal Oxide + Water
 Phosphorus   (V) oxide powder is sprinkled
 over distilled water

 Sulfur   dioxide gas is bubbled into distilled
        Metal oxide + water    metal hydroxide

   Solid Cesium Oxide is added to water

   Solid sodium oxide is added to distilled water

   Powdered strontium oxide is added to distilled

   Calcium oxide powder is added to distilled water

   Solid barium oxide is added to distilled water
Cmd         Na2O    MgO       Al3O2     SiO2        P4O10       SO3         Cl2O7

%Ionic      79      68        56        45          32          17          2

Solid       Ionic   Ionic     Ionic     Network     Molecular   Molecular   Molecular

Hydroxide   NaOH    Mg(OH)2   Al(OH)3   Si(OH)4     OP(OH)3     O2S(OH)2    O3Cl(OH)
Formula                                 SiO2+2H2O   H3PO4       H2SO4       HClO3

            Very    Basic     Ampho.    Slightly    Acidic      Stronger    Very Acidic
            Basic                       acidic                  Acid
    Hydrogen-Nonmetal + Water   Acidic Solution

 Hydrogen   Chloride gas bubbled into water
    Metal oxide + nonmetal oxide    metal ion attached to common
                            polyatomic ion

 Metal  oxide + carbon dioxide                         metal
   Carbon dioxide gas is passed over hot, solid
    sodium oxide

 Metal       oxide + sulfur dioxide             Metal
   Sulfur Dioxide is passed over solid calcium oxide
 Substances  break down by means of
  decomposition reactions
 The general form of a decomposition
  reaction is
     C     A+B
 Decomposition reactions are the opposite
  of combination or synthesis reactions
Decomposition of Metal Carbonate
 Heating  a metal carbonate always yields
  the metal oxide and carbon dioxide.
 MCO3       MO + CO2
 Powdered magnesium carbonate is
  heated strongly
 Solid calcium carbonate is strongly heated
     Metal Hydrogen Carbonate
 Heating a metal bicarbonate gives the
  metal oxide, carbon dioxide, and water.
 MHCO3     MO + H2O + CO2


      Sodium Hydrogen Carbonate is
 Solid
 strongly heated
               Heating the nitrates

   Most nitrates tend to decompose on heating to give the metal oxide,
    brown fumes of nitrogen dioxide, and oxygen.

   For example, a typical Group 2 nitrate like magnesium nitrate
    decomposes like this:
               2 Mg(NO3)2 =    2 MgO + 2 NO2 + 3 O2
   In Group 1, lithium nitrate behaves in the same way - producing
    lithium oxide, nitrogen dioxide and oxygen.

   The rest of the Groups, however, don't decompose so completely (at
    least not at Bunsen temperatures) - producing the metal nitrite and
    oxygen, but no nitrogen dioxide.
Decomposition of Metal Hydroxides
 Heating a metal hydroxide gives the metal
  oxide and water
 MOH          MO + H2O
   Metal Sulfite Decomposition
 Heating  a metal sulfite produces a metal
  oxide and sulfur dioxide
 MSO3 MO + SO2
 Solid calcium sulfite is heated in a vacuum
    Metal Chlorate Decomposition
 Heating a metal chlorate gives the metal
  chloride plus oxygen.
 MClO3      MCl + O2
  Electrolysis of Binary Compound
 Electrolysisof a molten salt (ionic
  compound) separates the substance into
  its elements.
 MN      M+N
         Ammonium Compound
 Ammonium
 Solid ammonium
  carbonate is heated
    (NH4)2CO3    =   2NH3 + 2CO2 + H2O
   Ammonium Hydroxide

                NH4OH  NH3+ H2O
            2007 Questions

(NH4)2CO3   =   2NH3 + 2CO2 + H2O
        Peroxide Decomposition
   Elephant’s Toothpaste
   Website:
   Genie in a Bottle Demo
   Website:
 Reactions Based on Reduction Potentials
             EMF Potential

 Reduction    and Oxidation
     Single replacement
          Cation Replacement
 There  are two types of single replacement
  reactions, in one, a metal or hydrogen
  replaces a positive ion
 M0 + A+B- M+B- + A0
       Replacement of Hydrogen
   Reaction of Magnesium and Different Concentrations of Acids
       Website:
   Hydrochloric Acid(g) + Magnesium(s)  Magnesium(II)Chloride(aq)
    + Hydrogen(g)
   2HCl(g) + Mg(s)  MgCl2(aq) + H2(g)

   Small piece of sodium metal is added to distilled water
   Website:
   Sodium(s) + Water(l)  Sodium Hydroxide(aq) + Hydrogen(g)
   2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
   ) Reaction of Potassium and Water
        Website:
   Potassium(s) + Water(l)  Potassium Hydroxide(aq) + Hydrogen(g)
   2K(s) + 2H2O  2KOH + H2(g)

   A strip of zinc is added to a solution of 6.0-molar hydrobromic acid

   Group I with water video
2007 Question
        Cation Replacement
 Reaction   of Zinc and Tin (II) Chloride
     Website:
 Zinc(s) + Tin (II) Chloride(aq)  Tin(s) +
  Zinc (II) Chloride(aq)
 Zn(s) + SnCl2(aq)  Sn(s) + ZnCl2(aq)
           Thermite Reaction
 2Al(s)   + Fe2O3 (s)  Al2O3 (s) + 2Fe(l)

 http://www2.chemie.uni-
   A solution of copper (II) sulfate is spilled onto a
    sheet of freshly polished aluminum metal.
   Bar of strontium metal is immersed in a 1.0 M
    copper (II) nitrate solution.
   A piece of copper wire is placed in a solution of
    silver nitrate
   A small piece of calcium metal is added to hot
    distilled water
   A solution of tin (II) nitrate is added to a solution
    of silver nitrate
A  mixture of powdered iron (III) oxide and
  powdered aluminum metal is heat
 A bar of zinc metal is immersed in a
  solution of copper (II) sulfate
 A piece of nickel metal is immersed in a
  solution of copper (II) sulfate
 Solutions of tin (II) chloride and iron (III)
  chloride are mixed
                        Cu+2 (aq) + Fe(s)  Cu(s) + Fe+2

                        Cu+2 (aq) + Zn(s)  Cu(s) + Zn+2

   Growing Crystals in Gels are a
    great activity you can use to
    demonstrate single replacement
   Solutions:
   1.    Saturated Sodium
    metasilicate- Flinn Scientific (CAT
    No. S0102) – Needs to be diluted
    to a density of 1.06 g/ml. About
    158 ml of the commercial solution
    diluted to one liter of solution will
    yield a proper density.
   2.    Commercial White Vinegar
   3.    1.0 M CuCl2 (13.5g/100ml
   4.    1.0 M Pb(NO3)2
    (33.1g/100ml H2O)
Pb+2(aq) + Zn(s)  Zn+2(aq) + Pb(s)
          Anion Replacement
 In the second, a halogen replaces another
  halogen as the negative ion.
 N20 + A+B-     A+N- + B20

 Chlorine gas is bubbled through a solution of
  potassium bromide
 Liquid bromine is shaken with 0.5M sodium
  iodide solution
 Chlorine gas is bubbled into a solution of sodium
Halogen Replacement
NaClO(aq)  2HCl(aq)  Cl (aq)  NaCl(aq)  H O( )
                         2                   2
    Cl (g)  2NaBr(aq)  2NaCl(aq)  Br (aq)
      2                                 2
    To prepare a saturated solution of aqueous bromine, mix equal volumes of 1.28 M
     NaBr, 1.28 M HCl, and household bleach. Prepare only as much solution as you
     need to the activity in working fume hood to avoid unnecessary exposure to bromine
     vapor. There is no need to store the bromine water since it is easily prepared. It may
     also be helpful to mix the solutions in a clear glass bottle allowing your students to
     view the color of elemental bromine.

    Discussion:
    Since the solubility of bromine in water at 25EC is 0.214 moles/liter , a saturated
     aqueous bromine solution can easily be prepared as needed by mixing equal
     volumes of a 1.28 M sodium or potassium bromide solution, a 1.28 M hydrochloric
     acid solution, and common household bleach. The three reagents react according to
     the equation:

    The reaction between bleach and hydrochloric acid produces elemental chlorine
     which then will replace the bromine in sodium bromide producing bromine and
     sodium chloride.
    A saturated solution of aqueous chlorine can be prepared in the same fashion. To
     prepare 100 ml a saturated aqueous solution of chlorine, mix 1.5 ml of concentrated
     HCl with 13 ml of bleach in 84 ml of water. The solubility of chlorine at 25EC is 0.092
     M (2)
2007 Question
    Special Red-ox Reactions
 Hydrogen  reacts with hot metallic oxide to
  produce the elemental metal and water
 Hydrogen gas is passed over hot iron(II)
  oxide powder
 Oxygen react with Metal Sulfides to
  produce Metallic Oxides and Sulfur
   Copper reacts with
    Concentrated Sulfuric
    Cu + 2 H2SO4  CuSO4+SO2+2 H2O

   Copper Reacts with
    Concentrated Nitric
     3Cu + 8HNO3  Cu(NO3)2+ NO + 4H2O
Typical Reactions
Oxidation States of Manganese

 Procedure
 Place 10 ml of a Water into Four Graduated Cylinders
 Place one tablet #1 into each Cylinder
 .01 M KMnO4 solution is in four small cylinders labeled
  A , B, N ( Place Tablet 1/10 ml water)
 To Flask A, Add 10 ml of 3M H2SO4
 MnO4- + H+
 To Flask B, add 10 ml of 5 M NaOH.
 MnO4- + OH-
 To Flask N add nothing.
 MnO4-
               Special Redox
   To Flask A add .01M NaHSO3 ( Tablet 2) slowly
    till you get a colorless Mn2+ ion.
   MnO4- + 5H++ HSO3- 3H2O + 2Mn2+ + 5SO42-
   To Flask N add .01M NaHSO3 ( Tablet 2)until a
    brown precipitate forms.
   2MnO4- + 3HSO3-          3SO42- + H++ H2O +MnO2
   To Flask B slowly add .01M NaHSO3 ( Tablet 2)
    until a green solution forms.
   2MnO4- + OH-+ HSO3-        2MnO42- + 2H2O +
             Special Redox
 Sulfite ion is readily oxidized to sulfate. On
  prolonged exposure to air, this oxidation
  occurs with atmospheric oxygen:
 2SO32-(aq) + O2(g) --> 2SO42-(aq)
 Sulfite or sulfur dioxide will decolorize
  permanganate. This de-colorization serves
  as a convenient test for sulfur dioxide:
 2MnO4-(aq) + 5SO2(g) + 2H2O(l) -->
  5SO42-(aq) + 2Mn2+(aq) + 4H+(aq)
2007 Question
                Special Redox
   Hydrogen chloride gas is oxidized by oxygen gas.
   (i) Balanced equation:
 (i) 2 HCl + O2  H2O + OCl2
 or 4 HCl + O2  2 H2O + 2 Cl2

   (ii) If three moles of hydrogen chloride gas and
    three moles of oxygen gas react as completely as
    possible, which reactant, if any, is present in
    excess? Justify your answer.
   (ii) O2 in excess; reacting on a 2:1 mole ratio, 3
    mol HCl requires only 1.5 mol of O2
)  Formation of a Silver Mirror
 Website:
 : Preparing Oxygen from Bleach
 Website:
              Special Redox
 An acidic solution of potassium dichromate is
  added to a solution of iron (II) nitrate.
 Acidified solutions of potassium permanganate
  and iron (II) nitrate are mixed together
 Solution of iron (II) chloride is added to an
  acidified solution of sodium dichromate
 A concentrated solution of hydrochloric acid is
  added to solid potassium permanganate.
              Special Redox
 A solution of potassium dichromate is added to
  an acidified solution of iron(II) chloride.
 A concentrated solution of hydrochloric acid is
  added to solid potassium permanganate.
 Solutions of potassium permanganate and
  sodium oxalate are mixed.
 A solution of sodium bromide is added to an
  acidified solution of potassium bromate
         Reactions Driven by
           and Precipitation
 Solubility
 Formation of Gases ( Increase in entropy)
 Formation of Water
 Coordinate Covalent Bond Formation
  ( Lewis Acid-Base)
 Formation Constants
            Formation of Water
   Metal Oxide + an Acid      Salt + Water
   Metal Hydroxide + an Acid       Salt + Water
   (a special type of reaction called neutralization)
   A 0.1 M nitrous acid solution is added to the
    same volume of a 0.1 M sodium hydroxide
   A 0.02 M hydrochloric acid solution is mixed with
    an equal volume of a 0.01 M calcium hydroxide
                Acid Base
 Solid   strontium hydroxide is added to a
  solution of nitric acid.
 (i) Balanced equation:
 (i) Sr(OH)2 + 2 H+  2 H2O + Sr2+
 (ii) How many moles of strontium
  hydroxide would react completely with
  500. mL of 0.40 M nitric acid?
 (ii) 0.10 mol strontium hydroxide
  Lewis Acid-Base Reactions (Coordinate
        Covalent Bond Formation)
 Ammonia  gas is mixed with hydrogen
 chloride gas.

 Methylamine   gas is bubbled into distilled
            Lewis Acid/ Base
 Phosphine    (phosphorus trihydride) gas is
    added to boron trichloride gas.

       Question: Which species acts as a
    Lewis acid in the reaction? Explain.
  Formation of Gas and Water
 Metal  Carbonate + an Acid Salt + Carbon
  Dioxide + Water
 Hydrogen iodide gas is bubbled into a
  solution of lithium carbonate
 Solid zinc carbonate is added to 1.0 M
  sulfuric acid.
 Carbon dioxide and Water- Carbon
  Dioxide is easily produced by the reaction
  of sodium bicarbonate and vinegar.
       Nonmetal Oxide and Metal
) Reaction of Carbon Dioxide and
 Website:

   CO2(g) + Ca(OH)2(aq)  CaCO3(s) + H2O(l)
2007 Question
  Metal hydrides + Water Metal
   Hydroxide + Hydrogen Gas
 Solid   calcium hydride is added to distilled

 Solid   sodium hydride is added to water
  Formation of Gas and Water
 Metal Bicarbonate (Hydrogen Carbonate)
  + an Acid       Salt + Carbon Dioxide +
 Excess hydrobromic acid solution is added
  to a solution of potassium hydrogen
 Ifone or both of the products in the double
  replacement reaction is insoluble in
  water, the reaction will occur.

   1.   All nitrates, chlorates, and acetates are soluble in water. Silver
    acetate is sparingly soluble.
   2.   Most common acids are soluble in water.
   3.   All common IA, and ammonium compounds are soluble in water.
   4.   All chlorides, bromides, and iodides are soluble in water except silver,
    mercury (I), and lead. HgI2 and HgBr2 are insoluble in water.
   5.   All sulfates are soluble in water except CaSO4, SrSO4, BaSO4,
    PbSO4, Hg2SO4. Ag2SO4 is sparingly soluble in water.
   6.   All carbonates, phosphates, oxides, and sulfites are insoluble in
    water but soluble in dilute acids except the IA and ammonium compounds.
   7.   The sulfides of all metals are insoluble in water except the IA, IIA,
    and ammonium sulfides.
   8.   All hydroxides are insoluble in water except the IA, Ca(OH)2,
    Sr(OH)2, and Ba(OH)2 hydroxides.
A  solution of sodium phosphate is added
  to a solution of aluminum nitrate
 A solution of potassium phosphate is
  mixed with a solution of calcium acetate
 A solution of sodium Iodide is added to a
  solution of lead (II) acetate
 A solution of lead(II) nitrate is added to a
  solution of potassium sulfate.
2007 Question
        Complex Ion Formation

 Often an ion in water solution is in a more complex
  species, in which the ion is bound to several water
 A complex ion consists of a central ion to which are
  bonded two, four, or six neutral or ionic species
  called ligands
 Lead and Zinc form complexes with hydroxide
 The hydroxides of lead and zinc are soluble in both
  acidic and basic solutions
 Hydroxides that have this property are called
Halide complexes

Al3+ + 6 F- <----------> [AlF6]3-          2.5 x 104
Al3+ + 4 F- <----------> [AlF4]-1          2.0 x 108
Be2+ + 4 F- <----------> [BeF4]2-          1.3 x 1013
Sn4+ + 6 F- <----------> [SnF6]2-          1.0 x 1025
Cu+ + 2 Cl- <----------> [CuCl2]-1         3.0 x 105
Ag+ + 2 Cl- <----------> [AgCl2]-1         1.8 x 105
Pb2+ + 4 Cl- <----------> [PbCl4]2-        2.5 x 1015
Zn2+ + 4 Cl- <----------> [ZnCl4]2-        1.6
Hg2+ + 4 Cl- <----------> [HgCl4]2-        5.0 x 1015
Cu+ + 2 Br- <----------> [CuBr2]-1         8.0 x 105
Ag+ + 2 Br- <----------> [AgBr2]-1         1.0 x 1011

Ammonia complexes

Ag+ + 2 NH3 <---------->     [Ag(NH3)2]+   1.6 x 107
Zn2+ + 4 NH3 <----------> [Zn(NH3)4]2+     7.8 x 108
Cu2+ + 4 NH3 <----------> [Cu(NH3)4]2+     1.1 x 1013
Hg2+ + 4 NH3 <----------> [Hg(NH3)4]2+     1.8 x 1019
Co2+ + 6 NH3 <----------> [Co(NH3)6]2+     5.0 x 104
Co3+ + 6 NH3 <----------> [Co(NH3)6]3+     4.6 x 1033
Cd2+ + 6 NH3 <----------> [Cd(NH3)6]2+     2.6 x 105
Ni2+ + 6 NH3 <----------> [Ni(NH3)6]2+     2.0 x 108
Cyanide complexes

Fe2+ + 6 CN- <----------> [Fe(CN)6]4-        1.0 x 1024
Fe3+ + 6 CN- <----------> [Fe(CN)6]3-        1.0 x 1031
Ag+ + 2 CN- <----------> [Ag(CN)2]-1         5.3 x 1018
Cu+ + 2 CN- <----------> [Cu(CN)2]-1         1.0 x 1016
Cd2+ + 4 CN- <----------> [Cd(CN)4]2-        7.7 x 1016
Au+ + 2 CN- <----------> [Au(CN)2]-1         2.0 x 1038

Complexes with other monodentate
Ag+ + 2 CH3NH2 <---------> [Ag(CH3NH2)2]+1   7.8 x 106
Cd2+ + 4 SCN- <----------> [Cd(SCN)4]2-      1.0 x 103
Cu2+ 2 SCN- <----------> [Cu(SCN)2]          5.6 x 103
Fe3+ 3 SCN- <----------> [Fe(SCN)3]          2.0 x 106
Hg2+ 4 SCN- <----------> [Hg(SCN)4]2-        5.0 x 1021
Cu2+ 4 OH- <----------> [Cu(OH)4]2-          1.3 x 1016
Zn2+ 4 OH- <----------> [Zn(OH)4]2-          2.0 x 1020
          Complex Ion Formation
 Aqueous sodium hydroxide is added to a saturated solution of
    aluminum hydroxide, forming a complex ion.
   (i) Balanced equation:

   (ii) If the resulting mixture is acidified, would the
    concentration of the complex ion increase, decrease, or remain
    the same? Explain.

   (a) (i)     Al(OH)3 + OH-  [Al(OH)4]-
   (ii) decrease; H+ will neutralize OH- and destroy the
          Formation Constants
   Excess concentrated aqueous ammonia is
    added to a solution of nickel (II) bromide
   Excess concentrated hydrochloric acid is added
    to a 1.0 M solution of cobalt (II) chloride
   A drop of potassium thiocyanate solution is
    added to a solution of iron (III) nitrate.
   Excess concentrated ammonia solution is added
    to a solution of nickel (II) sulfate
   Excess sodium cyanide solution is added to a
    solution of silver nitrate
Balancing Red-Ox Reactions
Red-Ox Continued
Red-Ox Under Basic Conditions
Red-Ox continued
 Where  in The Curriculum?
 Thermochemistry
 Stoichiometry
 Bonding and Molecular Structure
      Metal Oxide and Water
 Solid   potassium oxide is added to water.
 (i) Balanced equation:
 (i) K2O + H2O  2 K+ + 2 OH-
 (ii) If a few drops of phenolphthalein are
  added to the resulting solution, what would
  be observed? Explain.
 (ii) pink color; phenolphthalein is pink in an
  alkaline solution
           Anion Replacement
   (a) Chlorine gas, an oxidizing agent, is bubbled
    into a solution of potassium bromide at 25°C.
   (i) Balanced equation:
   (i) Cl2 + 2 Br–  2 Cl– + Br2
   (ii) Predict the algebraic sign of ∆S˚ for the
    reaction. Explain your reasoning.
   (ii) negative, a decrease in entropy as a gas
    converts into aqueous and a ion converts into a
           Precipitate formation
   A solution of barium chloride is added drop by
    drop to a solution of sodium carbonate, causing
    a precipitate to form.
   (i) Balanced equation:
   (i) 3 Ba2+ + H2CO3 + HCO3- + CO32-  3
    BaCO3 + 3 H+
   (ii) What happens to the pH of the sodium
    carbonate solution as the barium chloride is
    added to it?
   (ii) pH will decrease
          Cation Replacement
 1.  A strip of magnesium metal is added to
    an aqueous solution of silver nitrate.

        Question: Which substance is
    oxidized in the reaction?
 Solid  potassium chlorate is strongly

         Question: What is the oxidation
    number of chlorine before and after the
    reaction occurs?
        Complex Ion Formation
 3.   Solid silver chloride is added to a
    solution of concentrated hydrochloric acid
    to form a complex ion.

       Question: Which species acts as a
    Lewis base in the reaction? Explain.
               Acid Base
 4.A solution of Ethanoic (acetic) acid is
  added to a solution of barium hydroxide.

 Question: Explain why a mixture of equal
  volumes of equimolar solutions of acetic
  acid and barium hydroxide is basic.
                 Acid Base
 5.   Ammonia gas is bubbled into a solution
    of hydrofluoric acid.

       Question: Identify a conjugate acid-
    base pair in the reaction.
          Cation Replacement
 Zinc  metal is placed into a solution of
    copper (II) sulfate.

        Question: Describe the change in
    color that the original solution undergoes
    as the reaction proceeds.
A    solution of nickel (II) bromide is added to
    a solution of potassium hydroxide.

         Question: Identify the spectator ions
    in the reaction mixture.
 Hexane   is combusted in air.

       Question: When one molecule of
    hexane is completely combusted, how
    many molecules of products are formed?