# Predicting Reactions Predicting Reactions

Document Sample

```					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
CHEMICAL EQUATIONS
 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) +
PbI2(s)

   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) +
PbI2(s)
 Pb2+(aq) + 2I-(aq)       PbI2(s)
Balancing
 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
Reactions
 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
   http://boyles.sdsmt.edu/magburn/magnesium_burning.htm
   Reaction of Iron and Sulfur
   http://www.pc.chemie.uni-siegen.de/pci/versuche/english/v21-1.html
   Reaction of Potassium and Oxygen
   http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag
e08.htm
   Reaction of Lithium and Oxygen
   http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag
e02.htm
   Reaction of Lithium and Chlorine
   http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag
e04.htm
   Reaction of Sodium and Oxygen
   http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag
e05.htm
   Reaction of Zinc and Sulfur
   http://boyles.sdsmt.edu/znsulf/zincsul.htm
Nonmetal + Nonmetal Molecular
compounds
 PureSolid Phosphorus (White Form) is
burned in air

 Reaction   of Phosphorus and Chlorine
     Website:
http://boyles.sdsmt.edu/pwithcl/reaction_of
_white_phosphorus_and.htm
Reaction of Hydrogen and
Oxygen
Hydrides
 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
water
 Sulfur trioxide gas is bubbled into water
Nonmetal Oxide + Water
Oxyacid
 Phosphorus   (V) oxide powder is sprinkled
over distilled water

 Sulfur   dioxide gas is bubbled into distilled
water
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
water

   Calcium oxide powder is added to distilled water

   Solid barium oxide is added to distilled water
Demo
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
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
carbonate
   Carbon dioxide gas is passed over hot, solid
sodium oxide

 Metal       oxide + sulfur dioxide             Metal
sulfite
   Sulfur Dioxide is passed over solid calcium oxide
DECOMPOSITION REACTIONS
 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
Decomposition
 Heating a metal bicarbonate gives the
metal oxide, carbon dioxide, and water.
 MHCO3     MO + H2O + CO2

 http://www.chemguide.co.uk/inorganic/gro
up1/compounds.html

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
Decomposition
 Ammonium
Carbonates
 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:
http://boyles.sdsmt.edu/tp
aste/elephants.htm
   Genie in a Bottle Demo
   Website:
http://boyles.sdsmt.edu/g
eniebot/genie.htm
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
   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:
http://boyles.sdsmt.edu/sodwat/reaction_of_sodium_and_water.htm
   Sodium(s) + Water(l)  Sodium Hydroxide(aq) + Hydrogen(g)
   2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
   ) Reaction of Potassium and Water
        Website: http://www.chem.shef.ac.uk/webelements-
moov/K_H2O.mov
   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
2134266654801392897&q=rubidium+water
2007 Question
Cation Replacement
 Reaction   of Zinc and Tin (II) Chloride
     Website:
http://www.chemtopics.com/lectures/unit02
/lecture1/displace.htm
 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://boyles.sdsmt.edu/thermite/therm.htm
 http://www2.chemie.uni-
erlangen.de/education/medprak/videos/the
rmit_v.mpg
   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
strongly.
 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
reactions.
   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
H2O)
   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
bromide
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
Dioxide
   Copper reacts with
Concentrated Sulfuric
Acid
Cu + 2 H2SO4  CuSO4+SO2+2 H2O

   Copper Reacts with
Concentrated Nitric
Acid
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)
 MnO4- + H+
 MnO4- + OH-
 MnO4-
Special Redox
till you get a colorless Mn2+ ion.
   MnO4- + 5H++ HSO3- 3H2O + 2Mn2+ + 5SO42-
brown precipitate forms.
   2MnO4- + 3HSO3-          3SO42- + H++ H2O +MnO2
until a green solution forms.
   2MnO4- + OH-+ HSO3-        2MnO42- + 2H2O +
SO42-
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
   (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:
http://boyles.sdsmt.edu/agmirror/agmir.ht
m
 : Preparing Oxygen from Bleach
 Website:
http://boyles.sdsmt.edu/prepoxyg/preparati
on_of_oxygen_gas_from_b.htm

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
Special Redox
 A solution of potassium dichromate is added to
an acidified solution of iron(II) chloride.
 A concentrated solution of hydrochloric acid is
 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
solution
   A 0.02 M hydrochloric acid solution is mixed with
an equal volume of a 0.01 M calcium hydroxide
solution.
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
water
Lewis Acid/ Base
 Phosphine    (phosphorus trihydride) gas is

       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
Hydroxide
) Reaction of Carbon Dioxide and
Limewater
 Website:
http://boyles.sdsmt.edu/respira/respir.htm

   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
water

 Solid   sodium hydride is added to water
Formation of Gas and Water
 Metal Bicarbonate (Hydrogen Carbonate)
+ an Acid       Salt + Carbon Dioxide +
Water
 Excess hydrobromic acid solution is added
to a solution of potassium hydrogen
carbonate.
PREDICTIONS BASED ON
SOLUBILITY
 Ifone or both of the products in the double
replacement reaction is insoluble in
water, the reaction will occur.
SOLUBILITY RULES FOR COMMON IONIC
COMPOUNDS IN WATER

   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.
Solubility
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 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
molecules
 A complex ion consists of a central ion to which are
bonded two, four, or six neutral or ionic species
called ligands
 AMPHOTERIC
 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
amphoteric
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
ligands
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
complex
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
Organic
 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
   (ii) negative, a decrease in entropy as a gas
converts into aqueous and a ion converts into a
liquid
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
   (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?
Decomposition
 Solid  potassium chlorate is strongly
heated.


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.
Precipitation
A    solution of nickel (II) bromide is added to
a solution of potassium hydroxide.

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

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

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 307 posted: 4/12/2010 language: English pages: 110