Module 6: Chemical Reactions

1
Module 6 Chemical Reactions

• By Alyssa Jean-Mary
• Source Modular Study Guide for First Semester
  Chemistry by Anthony J. Papaps and Marta E.
  Goicoechea-Pappas

2
Types of Chemical Reactions

• Two types of chemical reactions
• Redox reactions (oxidation-reduction reactions)
  reactions where individual elements undergo a
  change in oxidation number
• Combination reactions, which are not all redox
  reactions
• Decomposition reactions, which are also not all
  redox reactions
• Disproportionation reactions
• Combustion reactions
• Single replacement (displacement) reactions
• Miscellaneous redox reactions (i.e. reactions
  which are not specifically any of the above redox
  reactions)
• Non-redox reactions
• Dissociation/Ionization reactions
• Double replacement (metathesis) reactions
• Precipitation reactions reactions where a water
  insoluble solid is formed
• Neutralization reactions (acid-base reactions)
  reactions where acids and bases react to form
  water, which is a weak electrolyte, and a salt
• Slightly ionized product formation reactions
  reactions where a slightly ionized product (i.e.
  weak electrolyte), such as a weak acid or a weak
  base, is formed
• Gas formation reactions reactions where a gas
  forms

3
Physical States in Chemical Reactions

• For both types of chemical reactions, the
  physical state of the reactants and the products
  are indicated using the following symbols
• gas (g)
• liquid (l)
• solid (s)
• aqueous (i.e. dissolved in water) (aq)

4
Non-Redox Reactions Dissociation/Ionization
Reactions

• Dissociation a process where a solid ionic
  compound separates into its ions in solution
• Ionization a process where an acid or a base
  separates into its ions in solution
• When the ions are separate in solution, they are
  each completely surrounded by water. They are
  said to be hydrated or solvated by water.
• An example of dissociation is shown below. This
  is the dissociation of NaCl.

5
Non-Redox Reactions Dissociation/Ionization
Reactions Electrolytes or Non-electrolytes

• Solutes that are water-soluble are either
  electrolytes (weak or strong) or non-electrolytes
• Electrolytes substances whose aqueous solutions
  conduct an electrical current
• An electrical current can be carried through an
  aqueous solution by the ions that are present in
  the solution thus, ions have to be present in an
  electrolyte.
• The strength of an electrolyte depends on two
  things
• the number of ions present in solution
• the charges of the ions present

6
Non-Redox Reactions Dissociation/Ionization
Reactions Strong Electrolytes

• Strong Electrolytes substances that completely
  ionize (i.e. have only ions present) when
  dissolved in water, and thus, conduct electricity
  when in solution
• The general equation for the dissociation/ionizati
  on reaction of a strong electrolyte
• AxBy -H2O---gt xAy yBx-
• The following slides show the substances that are
  considered strong electrolytes

7
Non-Redox Reactions Dissociation/Ionization
Reactions Strong Electrolytes Solubility Rules

• Below are the solubility rules. Use these rules
  to predict whether an ionic compound is soluble
  or not soluble in water.
• Any soluble salt is a strong electrolyte.

8
Non-Redox Reactions Dissociation/Ionization
Reactions Strong Electrolytes Acids and Bases

• Solubility for acids and bases
• Acids for all practical purposes, all are
  soluble in water
• Bases rule 7 on the solubility rules refers to
  their solubility, since it is talking about OH-.
• Those acids and bases that are strong
  electrolytes are only those that are strong acids
  and bases. Even if an acid or a base is soluble,
  it is not a strong electrolyte unless it is a
  strong acid or a strong base.

9
Non-Redox Reactions Dissociation/Ionization
Reactions Weak Electrolytes

• Weak electrolytes substances that partially
  ionize (i.e. have ions present, but also
  molecules present) when dissolved in water, and
  thus, partially conduct electricity when in
  solution
• The general equation for the dissociation/ionizati
  on reaction of a weak electrolyte
• AxBy lt--H2O---gt xAy yBx-
• The double arrow indicates that the reaction is
  reversible, which means that the reaction can
  occur in both directions (forward and backward).
  Thus, for weak electrolytes, in addition to the
  ions (xAy yBx-) present, the molecules of AxBy
  (i.e. the unionized specie) are also present in
  the solution.
• The following, when in aqueous solution, are the
  substances that are considered weak electrolytes
• Insoluble salts (i.e. any salt that the
  solubility rules indicates is not soluble in
  water)
• Weak acids (i.e. any acid that is not a strong
  acid (see the previous slide))
• Weak bases (i.e. any base that is not a strong
  base (see the previous slide))
• Water
• Certain gases (e.g. CO2, SO2)

10
Non-Redox Reactions Dissociation/Ionization
Reactions Non-Electrolytes

• Non-electrolytes - substances that do not ionize
  (i.e. have no ions present, only molecules
  present) when dissolved in water, and thus, do
  not conduct electricity when in solution
• The general equation for the dissociation/ionizati
  on reaction of a non-electrolyte
• CxHyOx -H2O---gt N.R.
• N.R. no reaction (here, it means no
  dissociation/ionization)
• The following are the substances that are
  considered non-electrolytes
• Organic compounds containing oxygen that dissolve
  in water, but do not dissociate or ionize when
  they are dissolved in water (for example,
  alcohols, whose general formula is CxHyOH, and
  sugars, whose general formula is CxH2xOx).

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Steps for Completing and Balancing
Dissociation/Ionization Reactions

• Step 1 Check the solubility rules to see if the
  compound is soluble
• If it is soluble and a strong electrolyte (i.e. a
  strong acid or a strong base), continue to step
  2.
• If it is soluble but not a strong electrolyte
  (i.e. if it is a weak electrolyte, especially a
  weak acid or a weak base, or a non-electrolyte),
  write N.R., indicating no reaction, since
  COMPLETE dissociation/ionization does not occur.
• If it is not soluble, write N.R., again,
  indicating no reaction.
• Step 2 Separate the compound into its two ions,
  writing them with their charges and (aq).
• Step 3 Balance the equation, following the same
  balancing rules learned previously.

12
Examples of Completing and Balancing
Dissociation/Ionization Reactions 1

• Complete and balance the following reactions
• Example 1 Li2SO4 --H2O--gt
• Step 1 By rule 5, it is soluble.
• Step 2 Li2SO4 --H2O--gt Li (aq) SO42- (aq)
• Step 3 __Li2SO4 --H2O--gt _2_Li (aq) __SO42-
  (aq), so the completed and balanced equation
• Li2SO4 --H2O--gt 2 Li (aq) SO42- (aq)
• Example 2 HNO3 --H2O--gt
• Step 1 By rule 3, it is soluble, and it is a
  strong acid, so it is a strong electrolyte.
• Step 2 HNO3 --H2O--gt H (aq) NO3- (aq)
• Step 3 __HNO3 --H2O--gt __H (aq) __NO3- (aq),
  so the completed and balanced equation
• HNO3 --H2O--gt H (aq) NO3- (aq)

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Examples of Completing and Balancing
Dissociation/Ionization Reactions 2

• Complete and balance the following reactions
• Example 3 AgCl --H2O--gt
• Step 1 By rule 4, it is not soluble, so there is
  no reaction
• AgCl --H2O--gt N.R.
• Example 4 NH4OH --H2O--gt
• Step 1 By rule 7, it is soluble, but it is a
  weak base, so it is a weak electrolyte, so there
  is no reaction
• NH4OH --H2O--gt N.R.
• Example 5 CH3OH --H2O--gt
• Step 1 It is an organic compound containing
  oxygen, so it is a non-electrolyte, so there is
  no reaction
• CH3OH --H2O--gt N.R.

14
Non-Redox Reactions Double Replacement
(Metathesis) Reactions

• In these reactions, the cation from one of the
  reactants is exchanged with the cation from the
  other reactant thus, the two reactants exchange
  partners.
• The general equation for the double replacement
  (metathesis) reactions
• AB CD ? AD CB
• Here, the first elements in each compound are
  the cations (i.e. A and C) and the second
  elements in each compound are the anions (i.e. B
  and D)
• The driving force behind these reactions is the
  formation of a weak electrolyte (see previous
  list)
• One or both of the products in a double
  displacement (metathesis) reaction MUST be a weak
  electrolyte. If neither of the products are weak
  electrolytes (i.e. if they are both strong
  electrolytes), then no reaction occurs, so write
  N.R..

15
Non-Redox Reactions Double Replacement
(Metathesis) Reactions Precipitation Reactions

• Precipitation reactions are reactions in which a
  water insoluble solid is formed.
• The general equation for precipitation reactions
• AB (aq) CD (aq) ? AD (s) CB (aq)
• Here, AD is either an insoluble salt or a
  slightly insoluble salt (i.e. a weak
  electrolyte), which is why it has the (s) next to
  it.
• To predict whether a precipitate (ppt) forms, use
  the solubility rules.

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Steps to Completing and Balancing Precipitation
Reactions

• Step 1 Exchange partners, writing the cation
  first for each new compound (i.e. keep the same
  first elements, just switch the second elements).
  When exchanging partners, dont exchange the
  subscripts on the partners, just exchange the
  elements and the polyatomic ions.
• Step 2 Predict the solubility of the two
  products using the solubility rules.
• If both products are soluble and not a weak acid
  or a weak base, then no reaction occurs, so write
  N.R..
• Step 3 Indicate the physical state of each
  product.
• Step 4 Find the correct formula for each of the
  products by crossing the charges.
• Step 5 Rewrite the equation, and then balance it.

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Example 1 of Completing and Balancing
Precipitation Reactions

• Example 1 Complete and Balance the following
  reaction
• Na2SO4 (aq) Sr(ClO3)2 (aq) ?

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Example 2 of Completing and Balancing
Precipitation Reactions

• Example 2 Complete and balance the following
  reaction
• Na2SO4 (aq) Li2CO3 (aq) ?

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Non-Redox Reactions Double Replacement
(Metathesis) Reactions Neutralization
(Acid-Base) Reactions

• Neutralization (acid-base) reactions are
  reactions in which an acid and a base react to
  produce a salt and water.
• The general equation for neutralization
  (acid-base) reactions
• HX BOH ? BX H2O
• (acid base ? salt water)
• To recognize an acid and a base, and thus a
  neutralization reaction, use the following
  definitions by Arrhenius
• An acid is a substance that ionizes in water to
  produce H. In other words, an acid has an H
  present in its formula, at the front of the
  formula.
• A base is a substance that ionizes in water to
  produce OH-. In other words, a base has an OH
  present in its formula, at the end of the
  formula.
• Since water, which is a weak electrolyte, is
  always formed in a neutralization (acid-base)
  reaction, a reaction always occurs.

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Steps to Completing and Balancing Neutralization
(Acid-Base) Reactions

• Step 1 Exchange partners combine the H from the
  acid and the OH from the base to form water
  combine what is left of the base with what is
  left of the acid, writing what is left of the
  base first. When exchanging partners, dont
  exchange the subscripts on the partners, just
  exchange the elements and the polyatomic ions.
• Step 2 Predict the solubility of the salt using
  the solubility rules.
• Step 3 Indicate the physical state of each
  product, remembering that water is a liquid (l).
• Step 4 Find the correct formula for the salt by
  crossing the charges.
• Step 5 Rewrite the equation, writing H2O as HOH
  for easier balancing (i.e. to balance OH as a
  group), and then balance it.

21
An Example of Completing and Balancing
Neutralization (Acid-Base) Reactions

• Example 1 Complete and balance the following
  reaction
• Al(OH)3 (aq) HClO2 (aq) ?

22
Non-Redox Reactions Double Replacement
(Metathesis) Reactions Slightly Ionized Product
Formation Reactions

• Slightly ionized product formation reactions are
  reactions that yield a weak acid or a weak base.
• The two different general equations for slightly
  ionized product formation reactions
• AB HX ? HB AX
• where AB is a salt, HX is an acid, and HB is a
  weak acid
• AX BOH ? AOH BX
• where AX is a salt, BOH is a base, and AOH is a
  weak base
• To recognize a slightly ionized product formation
  reaction, remember that if an acid or base is not
  one of the strong acids or bases, then it is a
  weak acid or base.

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Steps to Completing and Balancing Slightly
Ionized Product Formation Reactions

• Step 1 Exchange partners, writing the cation
  first for each new compound (i.e. keep the same
  first elements, just switch the second elements).
  When exchanging partners, dont exchange the
  subscripts on the partners, just exchange the
  elements and the polyatomic ions.
• Step 2 Check if the acid or base formed is weak.
  Remember that a weak acid or base is one that is
  not one of the strong acids or bases.
• If it is soluble and not weak, then there is no
  reaction.
• Step 3 Predict the solubility of the other
  product using the solubility rules.
• Step 4 Indicate the physical state of each
  product, remembering that a weak acid or base is
  aqueous (aq).
• Step 5 Find the correct formula for each of the
  products by crossing the charges.
• Step 6 Rewrite the equation, and then balance it.

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Examples of Completing and Balancing Slightly
Ionized Product Formation Reactions 1

• Example 1 Complete and balance the following
  equation
• AgClO2 (aq) HNO3 (aq) ?
• Example 2 Complete and balance the following
  equation
• AgClO4 (aq) HNO3 (aq) ?

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Examples of Completing and Balancing Slightly
Ionized Product Formation Reactions 2

• Example 3 Complete and balance the following
  reaction
• NH4NO3 (aq) NaOH (aq) ?
• Example 4 Complete and balance the following
  reaction
• LiNO3 (aq) NaOH (aq) ?

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Non-Redox Reactions Double Replacement
(Metathesis) Reactions Reactions with Gas
Formation

• Many of the weak acids and weak bases that are
  formed in double replacement reactions decompose
  into a gas and water
• The most common, both of which are weak acids,
  are
• H2CO3, which decomposes into CO2 and H2O
• H2SO3, which decomposes into SO2 and H2O

27
Steps to Completing and Balancing Reactions with
Gas Formation

• Step 1 Exchange partners, writing the cation
  first for each new compound (i.e. keep the same
  first elements, just switch the second elements).
  When exchanging partners, dont exchange the
  subscripts on the partners, just exchange the
  elements and the polyatomic ions.
• Step 2 Predict the solubility of the two
  products using the solubility rules.
• If both products are soluble and not a weak acid
  or a weak base, then no reaction occurs, so write
  N.R..
• Step 3 Indicate the physical state of each
  product.
• Step 4 Find the correct formula for each of the
  products by crossing the charges.
• Step 5 If H2CO3 or H2SO3 is one of the products
  formed, decompose them further, creating a gas
  (CO2 for H2CO3 and SO2 for H2SO3) and water
• Step 6 Rewrite the equation, and then balance
  it.

28
An Example of Completing and Balancing Reactions
with Gas Formation

• Example 1 Complete and balance the following
  reaction
• Na2CO3 (aq) HNO3 (aq) ?

29
Writing Double Replacement Reactions in Total
Ionic and Net Ionic Form

• The double replacement reactions shown above were
  all written in molecular form. In the molecular
  form of an equation, only complete formulas were
  used (i.e. the formulas were written as if all
  the substances existed as molecules, that they
  dont break up into ions).
• When strong electrolytes are dissolved in water,
  they ionize (i.e. they break up into ions), so
  instead of writing them as AB (aq), they should
  be written A (aq) B- (aq).
• For example, when NaCl (s) dissolves in water,
  instead of writing NaCl (aq), what should be
  written is Na (aq) Cl- (aq).
• To write double replacement reactions in total
  ionic form, strong electrolytes (i.e. those
  substances that are (aq), except for weak acids
  and weak bases) are written as their free ions.
• To write double replacement reactions in net
  ionic form, any ion that appears as an ion on
  both sides of the equation is cancelled from both
  sides of the equation. These ions that appear as
  ions on both sides of the equation are spectator
  ions. Spectator ions do not participate in the
  chemical reaction, which is why they appear as
  ions on both sides of the equation.

30
Steps to Writing Double Replacement Reactions in
Total Ionic and Net Ionic Form

• Step 1 molecular form Complete and balance
  the reaction as explained above.
• Step 2 total ionic form Check if the
  substances that are aqueous (aq) are strong
  electrolytes
• If they are strong electrolytes, break them up
  into their ions.
• If they are weak electrolytes, leave them as they
  are.
• Any substance that is not aqueous (aq) gets left
  how they are.
• Step 3 net ionic form Cancel any ion that
  appears as an ion on both sides of the equation.

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Example 1 of Writing Double Replacement Reactions
in Total Ionic and Net Ionic Form

• Example 1 Write the molecular form, the total
  ionic form, and the net ionic form for the
  following reaction
• MnCl3 (aq) Na2S (aq) ?

32
Example 2 of Writing Double Replacement Reactions
in Total Ionic and Net Ionic Form

• Example 2 Write the molecular form, the total
  ionic form, and the net ionic form for the
  following reaction
• Co(C2H3O2)2 (aq) H3PO4 (aq) ?

33
Reduction and Oxidation

• Reduction the gain of electrons
• For example, Li e- ? Li
• Oxidation the loss of electrons
• For example, Mg ? Mg2 2e-
• A reduction and an oxidation always have to occur
  together they cannot occur separately.
• To determine which specie has been oxidized and
  which has been reduced, the oxidation number of
  each must first be determined
• If the oxidation number has increased, meaning
  the substance has lost e-, then that substance
  has been oxidized.
• If the oxidation number has decreased, meaning
  the substance has gained e-, then that substance
  has been reduced.
• Reducing agent (reactant) reagent that donates
  the electron(s), which means that it has lost
  electrons, which means it has been oxidized.
• Oxidizing agent (oxidant) reagent that accepts
  the electron(s), which means that it has gained
  electrons, which means it has been reduced.

34
Examples Involving Reduction and Oxidation

• In the following redox reactions, identify which
  specie is oxidized and which specie is reduced.
  Also, identify which specie is the oxidant and
  which specie is the reductant
• Example 1 2 H2 (g) O2 (g) ? 2 H2O (g)
• Example 2 Zn (s) CuSO4 (aq) ? ZnSO4 (aq) Cu
  (s)

35
Redox (Oxidation-Reduction) Reactions
Combination Reactions

• Combination reactions result in the formation of
  one compound from simpler materials. Not all
  combination reactions are redox reactions only
  those that involve one or more free elements are
  redox reactions.
• The general equation for combination reactions
• A B ? AB
• where A and B can be elements or compounds
• Some specific examples of combination reactions
• Redox reaction 2 K (s) F2 (g) ? 2 KF (s)
• Redox reaction Cl2 (g) PCl3 (l) ? PCl5 (s)
• Not a redox reaction P4O6 (s) 6 H2O (l) ? 4
  H3PO3 (aq)

36
Redox (Oxidation-Reduction) Reactions
Decomposition Reactions

• Decompostion reactions result in a compound being
  broken down into simpler compounds or all the way
  down to its elements. Not all decomposition
  reactions are redox reactions only those that
  involve one or more free elements are redox
  reactions
• The general equation for decomposition reactions
• AB ? A B
• where A and B can be elements or compounds
• Some specific examples of decompostion reactions
• Redox reaction Ba(ClO3)2 (s) ? BaCl2 (s) 3 O2
  (g)
• Redox reaction 2 K2O (s) ? 4 K (s) O2 (g)
• Not a redox reaction 2 KOH (s) ? K2O (s) H2O
  (g)

37
Redox (Oxidation-Reduction) Reactions
Disproportionation Reactions

• Disproportionation reactions result in the same
  element in a specie undergoing both oxidation and
  reduction. This element thus has at least three
  oxidation states one oxidation state when it is
  part of the reactant (i.e. the first oxidation
  state) and two oxidation states, one higher than
  this first oxidation state and one lower than
  this first oxidation state, when it is part of
  both of the products.
• The elements that are most likely to undergo
  disproportionation
• N, P, O, S, Cl, Br, I, Mn, Cu, Au, Hg
• Some specific examples of disproportionation
  reactions, where only the oxidation numbers for
  the element which is undergoing a change in
  oxidation number are shown
• -1 -2
  0
• 2 H2O2 (aq) ? 2 H2O (l) O2 (g)
• 1 0
  3
• 3 AuCl (s) ? 2 Au (s) AuCl3 (aq)
• 0
  1
  -1
• Cl2 (g) 2 NaOH (aq) ? NaClO (aq) NaCl (aq)
  2 H2O (l)
• The first two of these examples appear to be
  decomposition reactions instead of
  disproportionation reactions. In
  disproportionation reactions, the same element is
  undergoing a change in oxidation number, but in
  decomposition reactions, two or possibly more
  elements are undergoing a change in oxidation
  number. So, these two are disproportionation
  reactions since the same element is undergoing a
  change in oxidation number, and not two or more.

38
Redox (Oxidation-Reduction) Reactions Combustion
Reactions

• Combustion reactions involve burning compounds
  containing carbon (C) and hydrogen (H) in the
  presence of O2 (g) to form CO2 (g) and H2O (l)
• The general equation for combustion reactions
• CxHy O2 (g) ? CO2 (g) H2O (l)

39
Steps to Completing and Balancing Combustion
Reactions

• Step 1 Write the products, which are always CO2
  (g) and H2O (l).
• Step 2 Balance the equation.

40
An Example of Completing and Balancing Combustion
Reactions

• Example 1 Complete and balance the following
  reaction
• C5H12 (l) O2 (g) ?

41
Redox (Oxidation-Reduction) Reactions Single
Replacement (Displacement) Reactions

• Replacement (displacement) reactions are
  reactions where one element displaces another
  element from a compound.
• An active metal can displace either a less active
  metal or hydrogen from its compound in solution.
• A halogen can displace a less active halogen from
  its compound in solution.
• Electromotive (activity) series arrangement of
  elements (metals and hydrogen (H) in one list
  halogens in another list) so that each element
  will displace, from an aqueous solution of its
  salt, any of those elements that follow it.
• There are basically three types of single
  replacement (displacement) reactions.

42
Redox (Oxidation-Reduction) Reactions Single
Replacement (Displacement) Reactions Type 1

• The first type of single replacement
  (displacement) reactions a free and chemically
  active metal displacing a less active metal from
  a compound
• The general equation for this type
• A BC (aq) ? AC B
• where A, a metal, displaces B from an aqueous
  solution containing BC

43
Steps to Completing and Balancing Type 1 Single
Replacement (Displacement) Reactions

• Step 1 Check the activity series to see if the
  free metal is before the metal in the compound
  (i.e. the first element) that it is going to
  displace
• If the free metal does come before it, then
  continue to step 2.
• If the free metal does not come before it, then
  there is no reaction, so write N.R..
• Step 2 Displace the metal in the compound with
  the free metal, ignoring the subscripts.
• Step 3 Find the correct formula for the metal
  that is now free.
• Step 4 Write the correct physical state after
  the now free metal.
• Step 5 Find the correct formula for the new
  compound by crossing the charges.
• Step 6 Predict the solubility of the new
  compound using the solubility rules, and write
  the correct physical state after the new
  compound.
• Step 7 Rewrite the equation, and then balance
  it.

44
Examples of Completing and Balancing Type 1
Single Replacement (Displacement) Reactions

• Example 1 Complete and balance the following
  reaction
• Pb (s) Au(ClO4)3 (aq) ?
• Example 2 Complete and balance the following
  reaction
• Ag (s) Hg(NO3)2 (aq) ?

45
Redox (Oxidation-Reduction) Reactions Single
Replacement (Displacement) Reactions Type 2

• The second type of single replacement
  (displacement) reactions a free and chemically
  active metal displacing hydrogen from acids or
  water
• The two different general equations for this
  type
• M HX (aq) ? MX H2 (g)
• M H2O (l) ? MOH H2 (g)
• where M, a metal, displaces H from an aqueous
  solution containing HX or H2O

46
Steps to Completing and Balancing Type 2 Single
Replacement (Displacement) Reactions

• Step 1 Check the activity series to see if the
  free metal can displace H either in H2O (l), H2O
  (g), or an acid, HX (aq)
• If the free metal can displace H in the compound
  it is in, then continue to step 2.
• If the free metal cannot displace H in the
  compound it is in, then there is no reaction, so
  write N.R..
• Step 2 Displace the hydrogen in the compound
  with the free metal, ignoring the subscripts.
• Step 3 Write H2 (g) as one of the products.
• Step 5 Find the correct formula for the new
  compound by crossing the charges.
• Step 6 Predict the solubility of the new
  compound using the solubility rules, and write
  the correct physical state after the new
  compound.
• Step 7 Rewrite the equation, and then balance
  it.

47
Examples of Completing and Balancing Type 2
Single Replacement (Displacement) Reactions

• Example 1 Complete and balance the following
  reaction
• K (s) H2O (l) ?
• Example 2 Complete and balance the following
  reaction
• Ni (s) HNO3 (aq) ?
• Example 3 Complete and balance the following
  reaction
• Cu (s) H2O (l) ?

48
Redox (Oxidation-Reduction) Reactions Single
Replacement (Displacement) Reactions Type 3

• The third type of single replacement
  (displacement) reactions an active halogen (VIIA
  non-metal) in the uncombined state displacing a
  less active halogen
• The general equation for this type
• X2 MY (aq) ? MX Y2
• where X2, a halogen, displaces Y, a less active
  halogen, from an aqueous solution containing MY,
  with the metal, M, not changing its oxidation
  state

49
Steps to Completing and Balancing Type 3 Single
Replacement (Displacement) Reactions

• Step 1 Check the activity series to see if the
  free halogen is before the halogen in the
  compound (i.e. the second element) that it is
  going to displace
• If the free halogen does come before it, then
  continue to step 2.
• If the free halogen does not come before it, then
  there is no reaction, so write N.R..
• Step 2 Displace the halogen in the compound with
  the free halogen, ignoring the subscripts.
• Step 3 Find the correct formula for the halogen
  that is now free.
• Step 4 Write the correct physical state after
  the now free halogen.
• Step 5 Find the correct formula for the new
  compound by crossing the charges.
• Step 6 Predict the solubility of the new
  compound using the solubility rules, and write
  the correct physical state after the new
  compound.
• Step 7 Rewrite the equation, and then balance
  it.

50
Examples of Completing and Balancing Type 3
Single Replacement (Displacement) Reactions

• Example 1 Complete and balance the following
  reaction
• Cl2 (g) FeBr3 (aq) ?
• Example 2 Complete and balance the following
  reaction
• I2 (s) NaF (aq) ?

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THE END