1. AP Chemistry Last Update: 9/24/2013

2.  Previous AP Chemistry exams…  consistently had several multiple choice problems requiring you to predict the products of a reaction.  always had a free response problem on chemical reactions  The new AP Chemistry exam (spring 2014)  will probably still emphasize chemical reactions (no one is really sure what’s going to be on the exam)

3. Nomenclature Formula of Reactants Reaction Conditions Type of Reaction A solution of copper (II) sulfate is spilled onto a sheet of freshly polished aluminum metal. CuSO 4 + Al  ? Element + Ionic Compound = Single Replacement A + BC  AC + B CuSO 4 + Al  Cu + Al 2 (SO 4 ) 3 3 CuSO 4 +2 Al  3 Cu + Al 2 (SO 4 ) 3 Description Balanced Chemical Reaction Products Reaction Pattern

4.  Certain key words and chemicals allow you to identify a reaction.  For each type of reaction, these key words/chemicals will be listed as “You just might have a _____ reaction if…”  This is blatant piracy from Jeff Foxworthy’s skit “You just might be a redneck if…” ▪ This was the equivalent of Chuck Norris facts in the early 1990’s.

5.  Play external video clip now  http://www.youtube.com/watch?v=_WAQGD a9pJ8 http://www.youtube.com/watch?v=_WAQGD a9pJ8

6.  You just might have a double replacement reaction if…  both reactants are soluble ionic compounds or  the reactants are a solube ionic compound and an acid.  Pattern:AB + CD  AD + CB  Examples:  A solution of copper (II) chloride is added to a solution of sodium sulfide. ▪ CuCl 2 + Na 2 S  CuS + 2 NaCl  Solutions of strontium nitrate and sodium sulfate are mixed ▪ Sr(NO 3 ) 2 + Na 2 SO 4  SrSO 4 + 2 NaNO 3

7. Fire at the Caribbean Company Oil Storage Depot (2009) Source: news.bbc.co.uk Week in Pictures (downloaded 10/23/2009)

8.  You just might have a combustion reaction if…  the problem includes words like “burned” or “heated”; and  the reactant is an organic compound, H 2, a metal, P 4, or S 8.  General Pattern:AB + O 2  AO + BO  In general, the products are all oxides (H 2 O, CO 2, Al 2 O 3, SO 2, SO 3, P 4 O 10 )  Examples:  Methane is burned in air:CH 4 + 2 O 2  CO 2 + 2 H 2 O  Butane is burned in air:2 C 4 H 10 + 13 O 2  8 CO 2 + 10 H 2 O  White phosphorous is heated in air:P 4 + 5 O 2  P 4 O 10  Magnesium ribbon is heated in air:2 Mg + O 2  2 MgO  note: ionic compounds do not burn when heated  If ionic compounds are heated, then it is most likely a decomposition reaction

9.  You might have a single replacement reaction if…  the reactants are an element and a compound.  General Patterns:  if the element is a metal (M):M + BC  MC + B  if the element is a non-metal (X):X + BC  BX + C  Examples:  Liquid bromine is shaken with a 0.5 M sodium iodide solution. ▪ Br 2 + 2 NaI  2 NaBr + I 2  A strip of magnesium metal is added to a solution of silver nitrate. ▪ Mg + 2 AgNO 3  Ag + Mg(NO 3 ) 2  Zinc metal powder is poured into a beaker of hydrochloric acid. ▪ Zn + 2 HCl  H 2 + ZnCl 2

10.  You just might have an acid-base reaction if…  the reactants are an acid and a base.  acids: H +, NH 4 +, or H 2 O  bases (B): OH -, O 2-, CO 3 2-, HCO 3 -, S 2-, NH 3, or H 2 O  General Pattern:HA + MB  MA + HB  Often, the reaction produces an ionic compound called a salt  there are a lot of exceptions, depending on the base ▪ Acid + OH -  H 2 O + salt ▪ Acid + O 2-  salt with OH - as the anion ▪ Acid + CO 3 2- or HCO 3 -  CO 2 + H 2 O + salt ▪ Acid + S 2-  H 2 S (smells like rotten eggs) + salt ▪ Acid + NH 3  salt with NH 4 + as the cation  When H 2 O acts as an acid it produces OH -  When H 2 O acts as a base, it produces H +

11.  Chemistry Joke: What does this mean?

12.  Solutions of potassium hydroxide and acetic acid are mixed.  KOH + HC 2 H 3 O 2  H 2 O + KC 2 H 3 O 2  Calcium oxide powder is added to distilled water.  CaO + H 2 O  Ca(OH) 2  Solid lead (II) carbonate is added to a 0.5 M solution of sulfuric acid  PbCO 3 + H 2 SO 4  CO 2 + H 2 O + PbSO 4  An excess of hydrochloric acid is added to solid zinc sulfide.  2 HCl + ZnS  ZnCl 2 + H 2 S  Ammonia is added to a solution of phosphoric acid.  3 NH 3 + H 3 PO 4  (NH 4 ) 3 PO 4

13.  Play external video clips now  http://www.youtube.com/watch?v=AkRvn0p XTiw http://www.youtube.com/watch?v=AkRvn0p XTiw  http://www.youtube.com/watch?v=tZZv5Z2I z_s http://www.youtube.com/watch?v=tZZv5Z2I z_s

14.  You just might have a combination reaction if…  both reactants are elements, or  two molecules are mixed, or  carbon dioxide is reacted with an oxide.  General Pattern:A + B  AB  multiple reactants  one product  molecular oxide + water often  an acid  ionic oxide + CO 2  CO 3 2-

15.  Examples:  Sulfur trioxide gas is bubbled through water. ▪ SO 3 + H 2 O  H 2 SO 4 ▪ This reaction is responsible for acid rain  Solid dinitrogen pentoxide is added to water. ▪ N 2 O 5 + H 2 O  2 HNO 3  Carbon dioxide is passed over hot, solid sodium oxide: ▪ CO 2 + Na 2 O  Na 2 CO 3 ▪ This reaction has been considered as a means of carbon sequestration.

16. Source: Wikimedia Commons (downloaded 9/24/2013)

17.  You just might have a decomposition reaction if…  there is only one reactant and  energy is added (light, electricity, or heat); or  a solid ionic compound is heated.  Note: heat can also mean a combustion reaction. The reactants in a decomposition reaction must not be flammable.  General Pattern:A  B + C  One reactant  multiple products  CO 3 2-  CO 2 + O 2-  HCO 3 2-  CO 2 + H 2 O + CO 3 2-  2 H 2 O 2  2 H 2 O + O 2  ClO 3 -, BrO 3 -, or IO 3 -  O 2 + Cl -, Br -, or I -

18.  Examples  Solid sodium hydrogen carbonate is strongly heated: ▪ 2 NaHCO 3  CO 2 + Na 2 CO 3 + H 2 O  Solid sodium carbonate is strongly heated: ▪ Na 2 CO 3  CO 2 + Na 2 O  A vial of ammonium sulfide is smashed, producing a foul smell of rotting organic matter: ▪ (NH 4 ) 2 S  2 NH 3 + H 2 S

19.  For each of the following lab situations, write the balanced molecular equation for the resulting reaction. 1. A strip of zinc is placed in a solution of nickel (II) nitrate. 2. Ethyne is burned in air. 3. Solid calcium carbonate is added to a solution of acetic acid. 4. Lithium metal is strongly heated in nitrogen gas.

20.  Due next class:  Download this PowerPoint from NetClassroom  Read/review Mr. Tom’s Guide to Chemical Reactions.  Predicting Chemical Reactions Worksheet 1  Due on Tuesday  Predicting Chemical Reactions Worksheet 2

21. AP Chemistry Last Update: 9/24/2013

22. Nomenclature Formula of Reactants Reaction Conditions Type of Reaction Reaction Pattern A solution of copper (II) sulfate is spilled onto a sheet of freshly polished aluminum metal. CuSO 4 + Al  ? Element + Ionic Compound = Single Replacement A + BC  AC + B CuSO 4 + Al  Cu + Al 2 (SO 4 ) 3 3 CuSO 4 +2 Al  3 Cu + Al 2 (SO 4 ) 3 Description Balanced Chemical Reaction Products

23. Identifying FactorsReaction Type and Pattern 2 elements or 2 molecular comp. or CO + O 2- Combination A + B  AB Identifying FactorsReaction Type and Pattern 2 ionic compounds or Ionic + acid Double Repl. AB + CD  AD + CB Organic compound or element is burned/heated AB + O 2  AO + BO Element + Compound Single Repl. M + BC  B + MC X + BC  C + BX Acids: H +, NH 4 +, H 2 O Bases (B): OH -, O 2-, CO 3 2-, HCO 3 -, S 2-, NH 3, H 2 O Acid-Base H + is transferred from acid to base HA + MB  MA + HC 1 reactant + energy Ionic comp. + energy Decomposition A  B + C

24.  Coordination compounds/coordination complexes have covalent bonds between a metal ion and a ligand.  The metal ion must… ▪ want more electrons and ▪ be able to pull electrons into a bond (high electronegativity). ▪ Transition metal cations (i.e. Cu 2+, Co 2+, Ni 2+ ) and main group metals (i.e. Pb 2+, Sn 4+ ) have these properties.  The transition metal is bonded to a ligand. ▪ Any species that has an unshared pair of electrons (NH 3, Cl -, H 2 O) ▪ In order to drive the formation of the coordination bond, the ligand must be present in large quantities. ▪ The only exception is thiocyanate (SCN - ). Even small quantities of thiocyanate can form a coordination compound.  Usually several ligands will bond to the metal ion ▪ The number of ligands per metal ion is called the coordination number.

25. Different colored coordination compounds of Nickel (II) [Ni(NH 3 ) 6 ] 2+ [Ni(en) 3 ] 2+ [NiCl 4 ] 2- [Ni(H 2 O) 6 ] 2+en Source: Wikimedia Commons (downloaded 9/24/2013)

26.  You just might have a coordination compound if…  You have a metal ion and… ▪ It must be either a main group metal ion or a transition metal ion.  You have a ligand and… ▪ Ligands must have a pair of unshaired electrons. ▪ Ligands must either be SCN- or be present in large quantities. ▪ Often words like “concentrated” or “excess” are used.  The metal and the ligand cannot react in any other way (i.e. double exchange won’t work).

27.  Skip straight to the net ionic equation.  General pattern:M x+ + n L y-  [M(L) n ] x-y  M x+ = metal ion  L y- = ligand  n = coordination number (usually 2, 4, or 6) ▪ usually you just arbitrarily pick a either 2, 4, or 6  [M(L) n ] x-y = the coordination complex

28.  Excess concentrated ammonia solution is added to a solution of nickel (II) sulfate.  metal = Ni 2+  ligand = NH 3  coordination number: 4 (just pick either 2, 4, or 6)  reaction:4 NH 3 + Ni 2+  [Ni(NH 3 ) 4 ] 2+  Potassium thiocyanate is added to a solution of iron (III) nitrate.  metal = Fe 3+  ligand = SCN -  coordination number:6  reaction:6 SCN - + Fe 3+  [Fe(SCN) 6 ] 3-

29.  Excess concentrated hydrochloric acid is added to a solution of 1.0 M cobalt (II) chloride.  try a double exchange rxn: 2 HCl + CoCl 2  CoCl 2 + 2 HCl  metal = Co 2+ ligand = Cl -  coordination number: 24  reaction: 2 Cl - + Co 2+  [Co(Cl) 2 ] 4 Cl - + Co 2+  [Co(Cl) 4 ] 2-  Excess concentrated sodium nitrate is added to a solution of iron (III) nitrate.  try a double exchange rxn: 3 NaNO 3 + Fe(NO 3 ) 3  Fe(NO 3 ) 3 + 3 NaNO 3  metal = Fe 3+ ligand = NO 3 -  coordination number: 26  reaction: 2 NO 3 - + Fe 3+  [Fe(NO 3 ) 2 ] + 6 NO 3 - + Fe 3+  [Fe(NO 3 ) 6 ] 3-

30. + Energy 

31.  Play external video clip now (heating copper (II) sulfate.  http://www.youtube.com/watch?v=M6IIbZx7 xvQ http://www.youtube.com/watch?v=M6IIbZx7 xvQ

32.  Almost always a dehydration reaction.  In the solid state, many transition metals form a hydrated crystal.  These crystals have water covalently bonded into their structure.  These bonds are weak and can be broken with a small input of energy. ▪ The coordination compound decomposes ▪ This is sometimes called a dehydration reaction ▪ This usually occurs at such high temperature that the water is released as water vapor.

33.  General Pattern  Hydrated ionic solid  anhydrous ionic solid + water  MA n H 2 O (s)  MA (s) + n H 2 O (g)  Examples:  Solid copper (II) sulfate pentahydrate is heated. ▪ CuSO 4 5 H 2 O  CuSO 4 + 5 H 2 O  Solid nickel (II) chloride hexahydrate heated. ▪ NiCl 2 6 H 2 O  NiCl 2 + 6 H 2 O

34.  You just might have a non-trivial redox reaction if…  One of your reactants is a multivalent metal such as Sn, Mn, Fe, or Cu; or  One of your reactants is Ag +, Cr 2 O 7 2-, MnO 4 -, CO, or O 2 2- ; or  The reaction happens in solution and the problem specifies whether the solution is acidic or basic.  Often, with non-trivial redox reactions, you will be given some of the products.  The challenge is balancing the reaction.  Skip straight to the net ionic equation.

35. Balancing non-trivial redox reactions 1. Separate the overall reaction into two half-reactions.  In each half-reaction, pair up the elements (i.e. the reactant with Cr is in the same half-reaction as the product with Cr). ▪ 4 substances  1 reactant and 1 product per half reaction ▪ If you do not have enough substances, use the same substance in both reactions. ▪ Substances with just H and O can be alone 2. Balance all elements except the H and O 3. Balance O using H 2 O. 4. Balance H using H + 5. Balance charge using e -. 6. (basic solutions only) For every H +, add an OH - to each side. Combine H + + OH -  H 2 O. Cancel out H 2 O. 7. Combine the half-reactions. 1. Multiply each half-reaction by a coefficient so that the e- cancel out. 2. Add the two half-reactions to get a net ionic reaction. 3. Cancel out anything which occurs on both sides.

36.  Examples (full procedure on board)  Fe 2+ + Cr 2 O 7 2-  Fe 3+ + Cr 3+ (in acid)  Cr 2 O 7 2- + C 2 O 4 2-  Cr 3+ + CO 2 (in acid)  Cu + NO 3 -  Cu 2+ + NO 2 (in acid)  Mn 2+ + H 2 O 2  MnO 2 (in base)

37.  Simple redox reactions can be broke into half- reactions as well.  Molecular reaction: M + AB  A + MB  Net Ionic reaction: M + A +  M + + A  Half reactions:M  M + andA +  A  Example: Magnesium metal is added to a solution of copper (II) chloride.  Molecular Reaction: Mg + CuCl 2  MgCl 2 + Cu  Net Ionic Reaction: Mg + Cu 2+  Mg 2+ + Cu  Half Reactions:Mg  Mg 2+ + 2 e-  Cu 2+ + 2 e -  Cu

38. We’re only half way through today’s presentation!

39. Identifying FactorsReaction Type and Pattern 2 ionic compounds or Ionic + acid Double Repl. AB + CD  AD + CB Organic compound or element is burned/heated AB + O 2  AO + BO Element + Compound Single Repl. M + BC  B + MC X + BC  C + BX Acids: H +, NH 4 +, H 2 O Bases (B): OH -, O 2-, CO 3 2-, HCO 3 -, S 2-, NH 3, H 2 O Acid-Base H + is transferred from acid to base HA + MB  MA + HC 1 reactant + energy Ionic comp. + energy Decomposition A  B + C Identifying FactorsReaction Type and Pattern 2 elements or 2 molecular comp. or CO + O 2- Combination A + B  AB Transition/main grp. metal + excess ligand Coordination M x+ + n L y-  [M(L) n ] x-y Hydrate is heatedDehydration MA n H 2 O  MA + n H 2 O (g) Multivalent metal Ag +, Cr 2 O 7 2-, MnO 4 -, CO or O 2 2- Acidic or basic soln. Non-Trivial Redox

40. 1. Solid tetraphosphorous decoxide is added to distilled water. 2. Equal volumes of 0.1 M solutions of lead (II) nitrate and magnesium iodide are combined. 3. Excess concentrated sodium chloride is added to a solution of tin (II) chloride. 4. What is the coefficient of H + after the following reaction is balanced? ▪ Sn 2+ + Cr 2 O 7 2- + H +  Sn 4+ + Cr 3+ + H 2 O 5. Iron metal is burnt in a thermic lance.

41.  Due next class:  Predicting Chemical Reactions Worksheet 2