Aqueous Reactions and Solution Stoichiometry (rev. 08/28/10)
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.
Know the symbols • g • s • l • aq • c
Drill • What is the difference between a “liquid solution” and an “aqueous solution” ?
Which of the following would be an electrolytic or non-electrolytic solution ? • NO • NaCl • PCl3 • CO2 • MgSO4 • Can you explain why?
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?
Are these weak or strong electrolytes? http://freshtomarket.com/01-02/electrolytes.jpg
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/chemical%20reactions/images/agcl.jpg
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
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?
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.
Write a Complete Ionic Equation and a Net Ionic Equation. KCl (aq) + AgNO3 (aq) → AgCl (s) + KNO3 (aq)
PracticeWrite Complete and Net Ionic Equations AgNO3 (aq) + KI (aq) → CuSO4 (aq) + Na2S (aq) → CoCl2 (aq) + NaOH (aq) → NiCl2 (aq) + KNO3 (aq) →
Net Ionic Equations • Try some more practice problems at: • http://www.nauticus.org/chemistry/chemnetionques.html
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.
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.
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.
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
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
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?
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.
Dilution MiVi = MfVf i is the initial concentration f is the final concentration
Molarity moles of solute Molarity = liters of solution Molarity is another way to express concentration.
Molality moles of solute Molality = kilograms of solvent Molality is another way to express concentration.
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.
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.
Titrations • You can use the dilution equation to solve titration problems, as long as the molar ratio is 1 to 1.
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