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					Chemical Reactions

     Chapter 4
           The Periodic Table
• Review
  – Arrangement is based on increasing ____ ____.
  – Groups or columns
     • Elements within a group have similar ____ and
       _____ properties.
     • Alkali metals (Group __), alkaline earth metals
       (Group __), halogens (Group __), and noble gases
       (Group ___).
  – s, p, d, and f blocks
Properties of Metals, Nonmetals
         and Metalloids
 Properties of Metals, Nonmetals
          and Metalloids
• The stair sep line separates the metals from the
  nonmetals
   – Metals are to the left of this line
       • ~80% of the elements are metals
   – Nonmetals are to the right of this line
   – Metalloids are on the line (in green)
       • Metalloids or semimetals exhibit properties intermediate
         between metals and metalloids.
           – For semiconductors such as silicon, the conductance increases
             with temperature
Typical properties exhibited by metals and
  nonmetals are given in Tables 4-3 and 4-4.
 Properties of Metals, Nonmetals
          and Metalloids
• Metallic character increases from top to bottom
  and decreases from left to right.
                      Less Metallic
         More
         Metallic
                      Periodic
                      Chart



• Nonmetallic character decreases from top to
  bottom and increases from left to right.
   – Best nonmetals are far to the right
          Aqueous Solutions
• An aqueous solution exists when a solute is
  dissolved in _____.
  – Formula is followed by (__)
• An electrolyte is a substance whose aqueous
  solution _____ ______ due to the
  movement of ions or charged particles.
  – An electrolyte produces ____ when dissolved
    in water. For example, NaCl dissolved in water
    to produce Na+ and Cl- ions.
          Aqueous Solutions
• The more ions produced by the substance,
  the stronger the electrolyte
  – Strong electrolyte – substances that conduct
    electricity well in dilute aqueous solutions
  – Weak electrolyte – substances that conduct
    electricity poorly in dilute aqueous solution
  – Nonelectrolyte – substances that do not conduct
    electricity in aqueous solutions
  DEMO: NaCl, acetic acid, and sugar water
  Generation of Ions in Solution
• Ions are generally produced from a
  substance in water by either dissociation or
  ionization.
  – Dissociation – an _____ compound separates
    into ions in solution
     • NaCl(s)
  – Ionization – a ______ compound separates or
    reacts with water to form ions in solution
     • HNO3(aq) + H2O(l)  H3O+(aq) + NO3-(aq)
  Generation of Ions in Solution
• Strong electrolytes. These are soluble in
  water.
  – Strong acids
  – Strong bases
  – Most soluble salts
• Weak electrolytes.
  – Weak acids
  – Weak bases
                Acids and Bases
• An acid is a substance that____ a proton.
  – In aqueous solution, this proton combines with
    water to form H3O+. All acids are ________
    substances.
  – Strong acids
     • Ionize almost completely to form ions in dilute aqueous
       solutions.
        – Original acid molecules largely do not exist in solution.
        – Ionization is near 100%
     • A list of strong acids is given in Table 4-5 (know
       these).
               Acids and Bases
• Representing reactions between strong acids and
  water.
         HClO3(aq) + H2O(l)      H3O+(aq) + ClO3-(aq)

• The double arrow indicates that the reaction
  proceeds in both directions. The reaction is
  ______. In reactions with double arrows, the
  limiting reactant is not all used up.
   – The longer arrow pointing to the right indicates the the
     reaction is product-favored.
   – Ionization is near ________, only a _____ amount of
     limiting reactant remains.
   – All strong acids react similarly in water. They are
     product-favored.
             Acids and Bases
• Weak acids ionize only _____ in dilute
  aqueous solutions.
  – Ionization is generally less than 5%.
  – A list of common weak acids is in Table 4.6.
       HCN(aq) + H2O(l)        H3O+(aq) + CN-(aq)
  – The reaction is also reversible, but the longer
    arrow points to the left indication that the
    reaction is ________.
     • Most of the limiting reactant is not used.
        Reversible Reactions

• Acetic acid/H2O reaction
• HCl/H2O reaction
• Al(NO3)3/NaOH reaction
            Acids and Bases
• Most acids are weak.
  – ______ acids are almost always weak.
     • The O-H bond is broken.
     • Demonstration with acetic acid, CH3COOH (show
       model).
• Write the reaction for the following acids
  with water.
  – HI, H2SO4, and (COOH)2
               Acids and Bases
• A base is a substance the produces____ ions in
  aqueous solutions. The ___ ions produced, the
  stronger the base. Know the strong bases in Table
  4-7.
• Generation of OH- ions in aqueous solutions
   – Dissociation of metallic hydroxides
                      H2O
            NaOH(s)         Na+(aq) + OH-(aq)
   – These dissolve and dissociate in water.
   – What do the arrows indicate in the reaction?
            Acids and Bases
• Generation of OH- ions in aqueous solutions
  – Bases that ionize in water
     NH3(aq) + H2O(l)        NH4+(aq) + OH-(aq)
  – These substances ionize in order to produce OH-
     • Mostly molecular substances
  – Most molecular substances that ionize to
    produce OH- are weak bases.
  – What do the arrows indicate about the limiting
    reactant?
           Acids and Bases
• Some ionic hydroxides are essentially
  insoluble in water.
          Cu(OH)2 CuOH+ + OH-
  – Only a small amount of OH- ions are generated
    due to solubility.
  DEMO: NaOH, NH3, and an insoluble hydroxide
    in water. Classify these bases.
     Acids and Bases – A Summary
• Strong acids and bases
   – The substance largely dissolves or reacts to produce ions
     (H3O+ or OH-)
      • Very small amount of limiting reactant remaining
   – Large arrow points toward the product side.
• Weak acids and bases
   – Very small amount of the substance dissolves or reacts with
     water to produce ions (H3O+ or OH-)
      • Large amount of limiting reactant remaining
   – Large arrow points toward the reactant side
  Determining if a Compound is
            Soluble
• Compounds whose solubility in water is
  less than 0.02 mol/L are generally classified
  as _______.
  – DEMO: Mg(OH)2 and NaCl
• Most substance are not infinitely soluble.
  – There is a limit to how much solid will dissolve
    in water.
Determining if a Compound is Soluble
  Determining if a Compound is
            Soluble
• Determine if the below compounds are
  soluble in water.
  – K2SO4, PbCl2, MgCO3, and NaOH
  – Acids and bases that ionize or dissociate only
    slightly can still be soluble in water.
     • CH3COOH and HF
  You do not have to memorize the solubility rules.
   Make sure, however, that you can use the table.
     Bonding, Solubility, Electrolyte Characteristics, and Predominant Forms of
                                    Solute in Water
                                    Acids                             Bases                                   Salts
                          Strong       Weak acids   Strong bases     Insoluble     Weak bases       Soluble       Insoluble
                           acids                                       bases                         salts          salts
Examples                HCl            CH3COOH      NaOH            Mg(OH)2        NH3            KCl            BaSO4
                        HNO3           HF           Ca(OH)2         Al(OH)3        CH3NH2         NaNO3          AgCl
Ionic or molecular      Molecular      Molecular    Ionic           Ionic          Molecular      Ionic          Ionic
compound
Solubility in water     Soluble        Soluble      Soluble         Insoluble      Soluble        Soluble        Insoluble

Magnitude of            Mostly         Small        Mostly          Small          Small          Mostly         Small
dissociation or         ionized        amount of    dissociated     amount of      amount of      dissociated    amount of
ionization in dilute                   ionization   or ionized      dissociation   dissociation                  dissociation
aqueous solutions
Solute mostly           Separate       Original     Separate ions   Original       Original       Separate       Original salt
present                 ions           acid                         base           base           ions
Arrows in chemical
equation
Reactant- or product-   Product-       Reactant-    Product-        Reactant-      Reactant-      Product-       Reactant-
favored                 favored        favored      favored         favored        favored        favored        favored
 Reaction in Aqueous Solutions
• Formation of insoluble ionic compounds
  – Pb(NO3)2(aq) + NaI(aq)  ?????
  – Will a solid compound form? How can you
    determine this??
  – Refer back to the solubility rules. Is there a
    combination that would be insoluble?
  – Al(NO3)3(aq) + NaOH(aq)  ?????
  – NaCl(aq) + Ni(NO3)2(aq)  ?????
      Representing the Reactions in
           Aqueous Solutions
• Formula unit equations
   – All complete formulas are shown
             2AgNO3(aq) + Cu(s)  2Ag(s) + Cu(NO3)2(aq)
   DEMO: Reaction
   Write the formula unit equations for the previous reactions
• Total ionic equations
   – Formulas illustrate the predominant form that is present in the
     aqueous solutions.
      • All species are still present.
   2Ag+(aq) + 2NO3-(aq) + Cu(s)  2Ag(s) + Cu2+(aq) + 2NO3-(aq)
   Write the total ionic equations for the previous reactions
  Representing the Reactions in
       Aqueous Solutions
• Net ionic equations
  – Only the species that react (i.e. change) are
    shown. Eliminate ions that don’t react. These
    are termed as spectator ions.
  2Ag+(aq) + Cu(s)  2Ag(s) + Cu2+(aq)
  Write the net ionic equations for the reactions
    done previously.
           Oxidation Numbers
• Reactions that involve the formation of ionic
  compounds include the transfer of electrons
  – NaCl and CaBr2
  – For these ionic compounds, oxidation numbers are
    used to keep track of electron transfers.
  – The oxidation number (or oxidation state) of the
    ions in these compounds is simply the charge on
    the respective ion.
     • NaCl and CaBr2
         Oxidation Numbers
• In molecular compounds, oxidation
  numbers are also assigned in order to aid in
  writing formulas and balancing equations.
  – Oxidation numbers are assigned on a per atom
    basis
  – Treat the rules in order of decreasing
    importance
  Page 138 (rules 1-8)
     Useful Rules in Assigning
       Oxidation Numbers
• The oxidation number of any free, uncombined
  element is zero
• The oxidation number of an element in a simple
  (monatomic) ion is the charge on the ion
• In the formula for any compound, the sum of the
  oxidation numbers of all elements in the
  compound is zero. In a polyatomic ion, the sum of
  the oxidation numbers of the constituent elements
  is equal to the charge on the ion
Table 4-10
    Assigning Oxidation Numbers
•   NaNO3
•   K2Sn(OH)6
•   H3PO4
•   SO32-
•   Cr2O72-
    Naming Binary Ionic Compounds
               IUPAC
• Generally a metal combines with a nonmetal
   – Less electronegative element first
      • Use element’s full name
   – More electronegative element second
      • Stem (drop last part) and add ‘ide’
   – Name the following ionic compounds
      LiBr, MgCl2, and Al2O3
   – Indicate the charge on metals that can have multiple
     charge states (transition metals and Groups IIIA (except
     Al), IVA, and VA)
      • SnO, SnO2, and FeBr3
   Naming Ionic Compounds with
         Polyatomic Ions
• Naming is very similar to the binary ionic
  compounds
• The polyatomic ion charge and name is
  taken from Table 2-3 and Table 4-11.
• Name the following ionic compounds
  – Al2(SO4)3, Ca(NO3)2, and (NH4)2SO4
      Naming Binary Molecular
           Compounds
• Nonmetal bonded to a nonmetal
  – The first element listed (most metallic) is
    named first
     • Receives full name.
  – The second element listed in the formula is
    named second
     • Drop the last portion of the name and add ‘ide’
  – Relative amounts of each element is indicated
    by a prefix
     • 2 – di, 3 – tri, 4 – tetra, 5 – penta, 6 – hexa
        Naming Binary Molecular
             Compounds
• Let’s name some binary molecular compounds
• SO3, OF2, and P4O6
• The minimum number of prefixes are used to
  name the compound unambiguously
   – mono, as a prefix, is not used
      • Exception is CO, carbon monoxide
• The final ‘a’ in a prefix is omitted when the
  element begins with ‘o’
   – As4O6
        Naming Binary Acids
• Compounds in which H is bonded to a
  Group VIA element other than O or to a
  Group VIIA element
• The pure compounds are named as typical
  binary compounds
• Aqueous solutions of the compounds are
  named by adding ‘hydro’ as a prefix and
  ‘ic’ as a suffix.
  – For the suffix, ‘ic’ the last portion of the
    element is dropped
      Naming Binary Acids
Compound   Name of pure   Name in
           substance      aqueous solution
HF         Hydrogen       Hydrofluoric
           fluoride       acid
HCl        Hydrogen       Hydrochloric
           chloride       acid
H2S        Hydrogen       Hydrosulfuric
           sulfide        acid
HBr        Hydrogen       Hydrobromic
           bromide        acid
              Naming Ternary Acids
• The acids are composed of H, O, and one more element
  (usually a nonmetal)
   – H2SO4
   – The ternary acids differ in the ____ of oxygen atoms contained
     in the acid
   – H2SO4 and H2SO3
   – The nonmetal must be able to have more than one oxidation state
• Two of the acids are chosen as a basis (reference)
   – The acid with the higher oxidation state number on the nonmetal
     or higher number oxygen atoms has a suffix ‘ic’
   – The acid with the lower oxidation state on the nonmetal or
     smaller number of oxygen atoms has a suffix ‘ous’
          Naming Ternary Acids
Formula   Oxidation   Name   Name    Oxidation   Name
          State                      State

HNO2                         HNO3

                             H2SO4


H2SeO3
       Naming Ternary Acids
• Ternary acids that have one less O atom
  than the ‘ous’ acid is formed by adding the
  prefix ‘hypo’ and the suffix ‘ous’
  – H3PO2 – hyposphosporous acid
     • What is the charge on the phosporus?
  – Name HClO and determine the charge on Cl
     • HClO3 is chloric acid and HClO2 is chlorous acid
       Naming Ternary Acids
• Acids containing one more oxygen atom
  than the ‘ic’ acid are named by adding ‘per’
  as a prefix and ‘ic’ as a suffix
  – HClO4 – perchloric acid
  – Name HIO4 and determine the oxidation state
    on I
     • HIO3 is iodic acid
          Naming Ternary Salts
• These compounds are formed by replacing the
  hydrogen in a ternary acid with another ion that
  is usually a metal cation (occasionally NH4+)
  – If the ternary acid ended in ‘ic’, the ‘ic’ is replaced
    with ‘ate’
  – If the ternary acid ended in ‘ous’, the ‘ous’ is
    replaced with ‘ite’
  – The ‘per’ and ‘hypo’ prefixes are retained with the
    salts
        Naming Ternary Salts
Formula Name              Formula Name

HClO    Hypochlorous      NaClO    Sodium
        acid                       hypochlorite
HClO2   Chlorous acid     NaClO2   Sodium
                                   chlorite
HClO3   Chloric acid      NaClO3   Sodium
                                   chlorate
HClO4   Perchloric acid   NaClO4   Sodium
                                   perchlorate
        Naming Ternary Salts
• Hydrogen is included in naming the salts
  and the ions
• Name the following ternary salts and ions
  – NaHSO4 and KH2PO4
  – H2PO2-1 and SO4-2
     • Page 145
Naming Ternary Acids and Salts
• Page 145, Problem-Solving Tip
Problems
           Redox Reactions
• If there is a change in the oxidation number
  of an element in the reaction, the reaction
  can be classified as redox.
  – 4Al(s) + 3O2(g)  2Al2O3(s)
  Assign oxidation states to all atoms.
  Which element gained a greater oxidation state
    and which element gained a lower oxidation
    state?
              Redox Reactions
• Oxidation – an ______ in oxidation state or
  apparent ____ of electrons.
• Reduction – a ______ in oxidation state or
  apparent ____ of electrons.
Oxidation and reduction occur _________ in a
  reaction (hence redox)
• Oxidizing agents – species that oxidize other
  substances
   – Gain electrons and are reduced
• Reducing agents – species that reduce other
  substances
   – Lose electron and are oxidized
             Redox Reactions
• In the first reaction with Al and O2, identify the
   substances that are reduced and oxidized. Identify
   the oxidizing agent and reducing agent.
• 3Zn(s) + 2CoCl3(aq)  3ZnCl2(aq) + 2Co(s)
Is this a redox reaction? Write the net ionic equaiton.
   Identify oxidation states, the reduced and oxidized
   species, and the reducing and oxidizing agents.
           Redox Reactions
• Al(NO3)3(aq) + 3NaOH(aq)  Al(OH)3(s)
  + 3NaNO3(aq)
• 4KClO3(s)  KCl(s) + KClO4(s)
In the last reaction, the same element (Cl) is
  oxidized and reduced. This is called a
  ______ reaction.
Obtain the information outlined in the
  previous slide for each reaction.
       Combination Reaction
• In this type reaction, two simpler substances
  combine to form a compound of the
  combined simpler substances.
  – 2Mg(s) + O2(g)  2MgO(s)
  – P4(s) + 10Cl2(g)  4PCl5(s)
  – CaO(s) + CO2(g)  CaCO3(s)
  Which of these reactions is a redox? When
    combining _______ the reaction is always redox.
     Decomposition Reactions
• In this type of reaction, a compound
  decomposed in simpler substances.
  – 2H2O(l)  2H2(g) + O2(g)
  – 2KClO3(s)  2KCl(s) + 3O2(g)
  – (NH4)2Cr2O7(s)  Cr2O3(s) + 4H2O(g) + N2(g)
  Determine which reactions are redox? If the
    reaction involves the formation of a ______,
    the reaction is always redox.
        Displacement Reactions
• In this reaction, one element displaces another
  in a compound. These reactions are always
  _____.
     2AgNO3(aq) + Cu(s)  2Ag(s) + Cu(NO3)2(aq)
  – Do you recall the total ionic and net ionic
    equations?
  – This is a displacement reaction where a more active
    metal displaces a less active metal in aqueous
    solution.
     • More active metal + salt of less active metal  Less
       active metal + salt of more active metal
Displacement Reactions
            • The most active
              metals are on top of
              the column.
               – These tend to react to
                 become more ______.
            • Elements at the
              bottom are least
              active.
               – These tend to become
                 or stay ______.
        Displacement Reactions
• Will the reactions proceed?
Cu(s) + Hg(NO3)2(aq)  Cu(NO3)2(aq) + Hg(s)
Sn(s) + FeCl2(aq)  SnCl2(aq) + Fe(s)
Write the net ionic equation for the reaction(s)
  that proceed? Is it redox?
          Displacement Reaction
• If the metal is active enough, it may displace H2
  from nonoxidizing acids such as HCl. In the
  reaction, the active metal becomes an aqueous salt.
Active metal + Nonoxidizing acid (most acids) 
  Hydrogen gas + Salt of the acid
• Any metal above hydrogen in the activity series will
  displace H2 from the acid.
   – Look at table 4-12
2Al(s) + 3H2SO4(aq)  3H2(g) + Al2(SO4)3(aq)
Write the net ionic equation.
      Displacement Reactions
•Will the below reactions proceed?
•Mg(s) + 2HCl(aq)  H2(g) + MgCl2(aq)
•Cu(s) + H2SO4(aq)  H2(g) + CuSO4(aq)
•Write the net ionic equation if the reaction
 proceeds.
DEMO:
         Displacement Reactions
• Which of the following metals will displace H2 from
  steam?
   – Co, Mg, and Sb
   – Write the net ionic equation for the reaction that proceeds
• Which of the following metals will react with cold
  H2O(l) to displace hydrogen?
   – Na, Al, Cr
   – Write the net ionic equation for the reaction that proceeds
   Demo: Calcium
      Displacement Reactions
• If a group VIIA nonmetal is active enough
  it will react with less active group VIIA
  nonmetal present in a salt.
  – Cl2(g) + 2NaBr(aq)  2NaCl(aq) + Br2(g)
• Activity series for group VIIA
  – F2 > Cl2 > Br2 > I2
  – The activity series progresses down the column
  DEMO: Several reactions with gases and salts
     Metathesis Reactions/Double
            Replacement
• Positive and negative ions appear to change
  ______ forming two new compounds
  – There is no change in _____ _____
  – Involves the removal of ____ in the reaction
     • Driving force for the reaction
           AX + BY  AY + BX
Ag(NO3)aq + NaCl(aq)  AgCl(s) + NaNO3(aq)
           Formula unit equation
   Metathesis Reactions/Double
          Replacement
• Three types of metathesis reactions
  – Formation of predominately nonionized
    molecules in solution
     • Weak or nonelectrolytes (e.g. water)
  – Formation of an insoluble solid
     • Insoluble precipitate
  – Formation of a gas such as H2
  Metathesis Reactions/Double
         Replacement
• Formation of predominately nonionized
  molecules in solution
  – Many of these reactions are acid-base reactions
     • Neutralization
  – In nearly all these ‘neutralization’ reaction,
    H2O is the nonelectrolyte formed
     • Formation of water is the driving force of the
       reaction
     • Additionally, a soluble or an insoluble salt is formed
        – Cation of the base and anion of the acid
         Acid/Base Reactions-A
          Metathesis Reaction
• Strong acid + strong base  water + salt
• Molecular equation
   – HBr(aq) + KOH(aq)  H2O(l) + KBr(aq)
• Total ionic equation
   – H+(aq) + Br-(aq) + K+(aq) + OH-(aq)  H2O(l) +
     K+(aq) + Br-(aq)
   – H+ is an abbreviation that we will use for H3O+
• Net ionic equation
   – H+(aq) + OH-(aq)  H2O(l)
   – This is the net ionic equation for all reactions between
     strong acids and strong bases
 Acid/Base Reactions-A Type of
      Metathesis Reaction
• Write the three equations for the below
  acid/base reaction.
 2HNO3(aq) + Ca(OH)2(aq)Ca(NO3)2(aq) +
                    2H2O(l)
   Acid/Base Reactions-A Type of
        Metathesis Reaction
• Reactions of weak acids with strong bases
  – CH3COOH(aq) + KOH(aq)  KCH3COO(aq) +
    H2O(l)
  What are the total ionic and net ionic equations?
  Note: The weak acids are only slightly ionized
  General representation for this type of reaction;
         HA(aq) + OH-(aq)  A-(aq) + H2O(l)
Precipitation Reaction-A Type of
      Metathesis Reaction
• Formation of an insoluble solid
• Use the solubility guidelines covered
  previously to determine if an insoluble ionic
  compound will form
  – Pb(NO3)2(aq) + K3PO4(aq)  ???
     • Write the total and net ionic equations
Precipitation Reaction-A Type of
      Metathesis Reaction
• KCl(aq) + CaSO4(aq)  ????
• HgCl2(aq) + KI(aq)  ?????

Write the total ionic and net ionic for
 equations that proceed
     Gas-Formation Reactions-A
     Type of Metathesis Reaction
• Gas formation is the driving force for this type of
  reaction
• 2HCl(aq) + CaCO3(s)  H2CO3(aq) + CaCl2(aq)
   – Total ionic and net ionic equations (but wait)
   – H2CO3(aq) dissociates
      • H2CO3(aq)  CO2(g) + H2O(l)
      • Most of the gas evolves
      • Total ionic and net ionic equations
      DEMO: Limiting reactant and CO2 production
      What should be left in the reaction beaker?
   Gas-Formation Reactions-A
   Type of Metathesis Reaction
• MnS(s) + 2HCl(aq)  H2S(g) + MnCl2(aq)
  – H2S is rotten egg gas
   Summary of Reaction Types
• Table 4-16
• You have to know how to classify the type
  of reaction and indicate if it is redox
Practice

				
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