Aqueous Reactions and Solution Stoichiometry

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Aqueous Reactions and Solution Stoichiometry

• (rev. 08/28/10)

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Objectives

• SWBAT
• Write molecular, complete ionic and net ionic
  equations.
• Distinguish between molecular, complete ionic and
  net ionic equations.
• Determine the solubility of double replacement
  reaction products using the Solubility Rules.
• Determine if a single replacement reaction occurs
  by using the Activity Series.

3
Know the symbols

• g
• s
• l
• aq
• c

4
Drill

• What is the difference between a liquid
  solution and an aqueous solution ?

5
Which of the following would be an electrolytic
or non-electrolytic solution ?

• NO
• NaCl
• PCl3
• CO2
• MgSO4
• Can you explain why?

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Weak vs Strong Electrolytes

• Use a single arrow to show a reaction with a
  strong electrolyte.
• Use a double arrow to show a reaction with a weak
  electrolyte.
• Does conducting electricity have anything to do
  with this topic?

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Are these weak or strong electrolytes?
http//freshtomarket.com/01-02/electrolytes.jpg
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Precipitation Reactions
Precipitation reactions are reactions that result
in the formation of an insoluble product. Make
sure to use an s to designate the solid that
precipitates. How do you determine if two
substances will create a precipitate?
http//www.iun.edu/cpanhd/C101webnotes/chemical2
0reactions/images/agcl.jpg
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Solubility Rules

• Use the Solubility Rules for Double Replacement
  Reactions.
• You must memorize the solubility rules for the AP
  exam and for a quiz in class.
• Distribute a copy of the
• Solubility Rules
• Activity Series

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Ionic Equations

• You need to know the difference between the
  following types of equations
• Molecular equations
• Complete ion equations
• Net ionic equations
• What is a spectator ion?

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How to write a Net Ionic Equation

• Write a balanced molecular equation.
• (see next slide for example)
• Rewrite the equation showing all strong
  electrolytes that dissociate (or ionize) in
  solution.
• Cancel out spectator ions.

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Write a Complete Ionic Equation and a Net Ionic
Equation.

• KCl (aq) AgNO3 (aq) ? AgCl (s) KNO3 (aq)

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PracticeWrite Complete and Net Ionic Equations

• AgNO3 (aq) KI (aq) ?
• CuSO4 (aq) Na2S (aq) ?
• CoCl2 (aq) NaOH (aq) ?
• NiCl2 (aq) KNO3 (aq) ?

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Net Ionic Equations

• Try some more practice problems at
• http//www.nauticus.org/chemistry/chemnetionques.h
  tml

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Activity Series

• Use the Activity Series for Single Replacement
  Reactions.
• You can use the activity series to determine if
  some reactions involving metals will occur.
• An activity series is a list of metals arranged
  in order of decreasing ease of oxidation.
• See the textbook for the activity series diagram.

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Activity Series Practice

• Try some practice problems. Use the Ch 8 Single
  Replacement Reactions worksheet.
• Use the Activity Series to determine if the
  reactions occur.

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Activity Series

• You will need to memorize the activity series for
  the AP exam.
• Look at the AP Reference packet. Take a good look
  at the Standard Reduction Potential chart.

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Strong Acids

• You need to memorize the list of strong acids and
  bases.
• Acids
• HCl
• HBr
• HI
• HClO3 chloric acid
• HClO4 perchloric acid
• HNO3 nitric acid
• H2SO4 sulfuric acid

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Strong Bases

• Bases
• Group 1A metal hydroxides (LiOH, NaOH, KOH, RbOH,
  CsOH)
• Heavy group 2A metal hydroxides
• Ca(OH)2 , Sr(OH)2 , Ba(OH)2

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What do you get when you mix an acid and a base?

• Any thoughts?
• A neutralization reaction
• Can you explain how the water is produced in a
  neutralization reaction?

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Oxidation-Reduction Reactions

• OIL oxidation is loss of electrons
• RIG reduction is gain of electrons
• See the textbook for the rules for assigning
  oxidation numbers.

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Dilution

• MiVi MfVf
• i is the initial concentration
• f is the final concentration

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Molarity

• moles of solute
• Molarity liters of solution
• Molarity is another way to express concentration.

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Molality

• moles of solute
• Molality kilograms of solvent
• Molality is another way to express concentration.

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Titrations

• Use titrations to determine the concentration of
  a solution.
• The point in a titration when stoichiometrically
  amounts are brought together is called the
  equivalence point.
• You titrate an unknown solution with a standard
  solution. Use an indicator to show when the
  equivalence point has been reached.
• The color change during a titration signals the
  endpoint which is very close to the equivalence
  point.

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Titration Calculations

• If you are given a volume and molarity for a
  substance, start the calculation with that.
• Convert to moles of what you know
• then use the molar ratios to convert to moles of
  the unknown substance
• Finally, use the volume of the unknown substance
  to convert to molarity.

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Titrations

• You can use the dilution equation to solve
  titration problems, as long as the molar ratio is
  1 to 1.

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Problems to Try

• 5, 6, 7, 9, 10, 11, 13, 16, 17, 18, 21, 26, 27,
  28, 35, 37, 39, 41, 43, 46, 51, 53, 54, 56, 59,
  60, 63, 65, 66, 67, 69, 71, 73, 76, 78, 81, 89, 90