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May 11, 2014 Dear Prospective AP Chemistry Students and Parents, Advanced Placement Chemistry is a course designed to be the equivalent of the general chemistry course taken during the first year of college by science majors. For some students, this course enables them to undertake, as freshmen, second year work in the chemistry sequence or to register for courses in other fields where general chemistry is a prerequisite. For other students, the AP Chemistry course fulfills the laboratory science requirement and frees time for other courses. AP Chemistry is a rigorous math-based course, with a strong laboratory component. It is intended for students who have demonstrated a willingness to commit considerable time to studying and completing assignments outside of class, and who have successfully completed a prior course in chemistry, preferably Honors Chemistry. Since passing the AP exam may qualify the student to by-pass a first-year college chemistry course, AP Chemistry should not be considered "college prep." Rather, this is a college class, with college level expectations for behavior, participation, and effort. REQUIRED materials: Scientific calculator or graphing calculator (must have LOG key) TEXTBOOK: You will be required to pick up your textbook from the school WHEN THERE ARE NO LONG LINES in the bookroom (during classes, after busses leave, or week after school ends). The book we will be using is: Chemistry, 10th edition by Brown, Lemay, & Bursten Summer Packet Assignment: The AP Chemistry exam is offered in the beginning of June, so we require that students complete summer review requirements prior to the start of school. This is vital in assuring that our students are guided in the best way possible. *Note: We will be utilizing the WebAssign Online Homework and the billing is applied per class. RECOMMENDED material: AP Chemistry Study Guide: “Princeton Review’s Cracking the AP: Chemistry” has been most notable (May be purchased from: Barnes and Nobles, Borders, or Amazon.com) The SUMMER ASSIGNMENT checklist is typed on the first page of the Basics of Chemistry Packet. This material should be a review of material learned in your prior chemistry course. Please follow those directions carefully. An exam over the material will occur the first week of class. The assignment will be collected and you will be held accountable for the chapter notes and memorization of charts. Please be sure to spend the time to read through the entire packet very carefully! We hope you are excited to be enrolled in this class. We look forward to meeting all of you in the fall. Have a wonderful summer! Sincerely, Mrs. Matynowski & Mrs. Ismail West Bloomfield High School For questions or problems, please e-mail at: [email protected] or [email protected] 1 AP Chemistry Name__________________________________ Basics of Chemistry Packet The material included in this packet covers approximately the first 3 chapters of AP Chemistry. You may use your textbook to help you review the material. The following material should be review for most of you and we recommend that you begin this a few weeks before school resumes. (Not too early - so it stays fresh)! Please initial and check off the following before the first day of school: Complete Summer Packet Initials_______ Outline in PEN/PENCIL the first three chapters of the textbook (not typed!) Chapter 1 Introduction: Matter and Measurement Initials ________ Chapter 2 Atoms, Molecules, and Ions Initials ________ Chapter 3 Stoichiometry Initials ________ Memorize Polyatomic Ion Sheet (tips on back) Initials _______ There are plenty of games online: http://www.sporcle.com/games/RyanWitchey/Chem_Anions Memorize Solubility Chart Initials _______ The chapter outlines must be hand written! The objective of the outlines is for you to read and become familiar with the content material. Focus on key vocabulary, equations, and processes. We recommend that you look at and understand each sample exercise while outlining each chapter. DO NOT TAKE NOTES ON THE CHAPTER SUMMARY!! A. Significant Figures. Review Significant Figures in the textbook, as needed. Complete the following questions. 1. How many significant figures are in each of the following measurements? a. 35.409 grams _________ b. 100.0 ml ___________ c. 0.044 grams _________ d. 4.260 x 1023 molecules ___________ 2. Compute the correct answer using significant figures. a. 23.01 grams + 7.7 grams + 9.110 grams = ___________________ b. 23. 1 grams x 7.71 grams x 9.100 grams = ___________________ 3. Compute the correct answer using significant figures. a. What is the density of a hydrochloric acid solution that has a mass of 17.84 grams and occupies 14.0 milliliters? (density is g/ml) b. What is the volume, in L, required of nitric acid if the mass of the acid is 32.0 grams? (The density of nitric acid is 1.251 g/ml). B. Nomenclature 1. Naming binary molecular compounds: Do not reduce molecular compounds. Remember that these are compounds made of 2 or more NON-METALS. 1. Use prefixes (mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-) 2. If there is one atom of the first element, you do not need the “mono-“ 3. Name ends in –ide. Example: N2F4 dinitrogen tetrafluoride CO carbon monoxide 2. Naming binary ionic compounds or ternary compounds: You should reduce ionic compounds. Remember that these are compounds made of at least 1 METAL. Write the name of the metal (it is always written first.) as it appears on the periodic table. Check on the periodic table to see if the METAL has a variable-charge. If it has more than one charge, you must use ROMAN numerals. (I, II, III, IV, V, VI, VII, VIII, IX, X) Memorize these now if you do not know them. Binary: Write down the non-metal, ending with –ide. Ternary: Write down the polyatomic ion, ending with –ite, -ate, or –ide. CUT OUT POLYATOMIC ION SHEET 2 3. Names and Formulas of Acids and Bases Acid - a compound that produces hydrogen ions when it is dissolved in water. Usually seen as H+ X- (H+ is the hydrogen ion; X- is the anion) Table 1. Chart for Naming Acids Anion Ending **Example Acid Name -ide sulfide : S2hydro - (stem)- ic acid 2-ite sulfite : SO3 (stem) - ous acid -ate sulfate : SO42(stem) - ic acid **Example hydrosulfuric acid sulfurous acid sulfuric acid Base - a compound that produces hydroxide ions when it is dissolved in water. Naming Rules : These are named the same as ionic compounds, cation + anion Example: NaOH Sodium hydroxide 4. Review the rules above and name the following compounds. a. BO3 b. Ca3P2 c. SeO4 d. Cl3O2 e. TeI5 f. Se2N4 g. OF8 h. As4Te7 i. Ba(CH3COO)2 j. Ti(CN)3 k. K2S l. CoCO3 m. Co3N2 n. NaClO3 o. LiNO3 p. MgSO4 q. Mn(PO4)2 r. RbMnO4 s. CsOH t. Pd(ClO4)4 u. Fe2S3 v. Sn(OH)2 w. Ni(NO2)2 x. K2Cr2O7 y. In(NO3)3 z. YI3 5. Name the following Acids a. H2S b. H2CrO4 c. HCl d. H3P e. HMnO4 f. HBr g. H2SO4 h. HClO4 i. HC2H3O2 j. HNO2 3 6. Write the formulas for these names. a. tetrasilicon triarsenide b. diselenium hexabromide c. diphosphorus monoxide d. octasulfur trioxide e. carbon monoxide f. phosphorus hexachloride g. silicon heptaiodide h. pentaboron triselenide i. nickel II nitrite j. aluminum perchlorate k. copper II carbonate l. cadmium sulfate m. mercury I nitrite n. hafnium selenide o. ruthenium III sulfate p. yttrium carbonate q. gallium III selenide r. osmium IV chromate s. niobium V sulfate t. ruthenium IV phosphate u. hexaoxygen difluoride v. magnesium sulfide w. calcium phosphide x. tetrarsenic hexaoxide y. lead IV chloride z. ruthenium VI sulfate Write the formulas for the following acids. a. phosphorous acid b. nitric acid c. sulfuric acid d. oxalic acid e. hydrofluoric acid f. boric acid g. hydrocyanic acid h. hypochlorous acid i. carbonic acid j. chlorous acid C. Balance the following equations and identify the type of reaction. Tip on balancing: If there is the same polyatomic ion on both sides of the equation, balance that compound first! If not, begin with the most complex compound and work from there. This usually helps. You may use fractions, but be sure your final answer is in whole numbers. ____N2 ____Ca3N2 (s) ____Fe2O3 (s) ____Fe(s) + 12. ____C3H8 + ____O2 ____CO2 13. ____NaCl + ____Br2 10. ____Ca(s) 11. + ____O2 (g) + ____NaBr ____H2O + ____Cl2 4 D.Predicting Products of a Chemical Reaction REFER to PREDICTING PRODUCTS GUIDE at end Predict the products for the following chemical equations. Classify each reaction as (C) Combustion, (SD) Single Displacement, (DD) Double displacement, (D1-6) Decomposition, or (S) Synthesis. Then, write the balanced chemical equation. Indicate the type of reaction on the line to the left of the equation. REFER TO GUIDE AT END OF PK. 14. __DD___ aluminum sulfate + calcium phosphate Al2(SO4)3 + Ca3(PO4)2 15. ________ 2Al(PO4) + 3CaSO4 magnesium chloride + silver nitrate 16. ________ potassium chlorate 17. ________ hydrogen gas + oxygen gas 18. ________ silver metal + copper (II) nitrate 19. ________ sulfurous acid 20. ________ copper (I) oxide + sulfuric acid 21. ________ nitrogen gas + hydrogen gas ammonia gas 22. ________ sodium iodide + chlorine gas 23. ________ copper (II) hydroxide 24. ________ ammonia gas (NH3) + hydrochloric acid (Single product) 25. ________ potassium metal + water (H+OH-) 26. _______ iron + oxygen gas (will form Fe+3) 27. ________ aluminum metal + sodium acetate 28. ________ gallium hydroxide + calcium sulfate 29. ________ calcium chlorate 30. ________ tungsten (V) chlorate + silver nitride 5 31. ________ barium chloride + sodium hydroxide 32. ________ tin metal + fluorine gas (Sn4+) 33. ________ potassium iodide + bromine gas 34. ________ octane(C8H18) + oxygen gas (remember octane is a hydrocarbon) 35. ________ sodium chloride + sulfuric acid 36. ________ glucose(C6H12O6) + O2 (glucose reacts as a hydrocarbon) 37. ________ potassium hydroxide + phosphoric acid 38. ________ iron (II) sulfide + hydrochloric acid 39. ________ magnesium + nitrogen gas D. Stoichiometry Throughout the year, you will see problems involving compounds made primarily of C and H. These are called hydrocarbons, or alkanes. You should become familiar with the first 10 normal alkanes. Methane CH4 Hexane C6H14 Ethane C2H6 Heptane C7H16 Propane C3H8 Octane C8H18 Butane C4H10 Nonane C9H20 Pentane C5H12 Decane C10H22 A handy way to remember the top 4 is with “Me Eat Peanut Butter!” You may use the “times 2, plus 2” rule to remember the ratio of C to H. e.g. octane: I know “octa-“ refers to 8 carbons, so 8 x 2 = 16 + 2 = 18 H Another interesting fact about hydrocarbons: When you burn (combustion) compounds with H and C (generally with O also), you always produce CO2 + H2O. ex: CH4(g) + 2O2 (g) CO2 (g) + 2H2O (g) 40. Write the balanced equation for the combustion of: a) propane b) butane 41. If 510.0 grams of propane were combusted in oxygen, how many grams of CO2 were produced? (Use the balanced equation above, then use stoichiometry.) 6 ANSWER ALL OF THE FOLLOWING, # 42 – 72 ON SEPARATE PAPER!! YOU MUST SHOW WORK FOR FULL CREDIT!! E. Limiting Reagents When one chemical is used up, the reaction stops. The limiting reagent is the reactant that is used up in the reaction. The excess reagent is the reactant that you have in excess after the reaction is complete. “Grilled Cheese Party” Recipe for a plain grilled cheese sandwich: 1 Cheese + 2 Bread 1 Grilled Cheese Sandwich Your dad went to Costco and bought one of those 100 singles of American Cheese (he also stocked up on the pretzels, chips, nachos, dip, and beverages). It was party time, so the party is hopping, and people are ready for what they came for…the Grilled Cheese Sandwiches!! So, you’re all going to get it started and you notice that dad FORGOT TO BUY LOAVES OF BREAD. You only have a pack of bread with 6 slices of bread. a) How many grilled sandwiches can you make?_________ (3) b) In a sense, 100 moles of cheese were allowed to react with 6 moles of bread, so how many moles of grilled cheese sandwiches could you produce?________________ (3 moles) c) What is the limiting reagent? ________________. (bread) 42. If I began with 11.0 g AgNO3 and 10.0 g Na2SO4, how many grams of Ag2SO4 can I make? Na2SO4 + 2AgNO3 2NaNO3 + Ag2SO4 F. Molecular Weight, % Composition, Empirical Formulas 43. Find the molecular weight (molar mass) of each of these compounds. a. RbOH b. Na2Cr2O7 c. AlBr3 d. Ba3(PO4)2 e. Fe(NO3)2 4H2O 44. Determine the molecular weight of each of the following. [Round to tenths place (0.1)] a. Ga(NO3)3 b. Y2(CO3)3 c. CoCl2 6H2O (do not multiply) 45. Determine the % of chlorine in each of these compounds. a. LiCl b. HClO4 c. AlBr3 d. Mg(ClO2)2 46. Determine the mass percent (% composition) a. % C in Al2(CO3)3 b. % O in Na2Cr2O7 47. How many moles are represented in each of these samples? a. 150. molecules of H2O b. 200.0 grams of H2O c. 500. atoms of Cu d. 500.00 grams of Fe 48. a. How many moles are in 58.6 g of AgNO3? b) How many formula units is this? 49. Determine the mass in grams of each of the following. a. 3.00 x 1020 molecules of O2 b. 4.66 moles of O2 c. a single molecule of O2 d. 4.50 x 1021 formula units of KOH e. 0.00255 moles of KOH 50. Ascorbic acid (vitamin C), C6H8O6, is an essential vitamin. It cannot be stored by the body and therefore must be present in the diet. a. What is the molecular weight of ascorbic acid? b. If you were to take a vitamin C tablet everyday, with 1500. g of ascorbic acid, how many moles would you ingest? c. How many molecules of C6H8O6 are you taking? 7 51. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when it dissolves in water. It is marketed as “Nutra-Sweet”. The molecular formula of aspartame is C14H18N2O5. a. What is the molecular weight of aspartame? b. How many molecules of aspartame are present in 15.0 grams of the compound? c. Calculate the mass of 3.56 moles of aspartame. d. How many molecules are in 5.900 mg of aspartame? e. What is the mass in grams of 21.66 x 1015 molecules of aspartame? f. What is the mass in grams of one molecule of aspartame? 52. A compound contains 22.1% Al, 25.4 % P, and 52.4 % O. What is the empirical formula for this compound? 53. A particular compound contains 25.93% N and 74.07 % O. What is the empirical formula? 54. An organic compound containing 8.28 g C and 1.72 g H is analyzed. What is the empirical formula? If the molecular weight is 58.0 g/mol, what is the molecular formula? 55. A compound that contains only carbon, hydrogen, and oxygen is 48.38% C, 8.12 % H, and 43.50 % O. What is the empirical formula for this compound? 56. The active ingredient in photographic fixer solution contains sodium, sulfur, and oxygen. Analysis of this sample shows that the sample contains 0.979 g Na, 1.365 g S, and 1.021 g O. What is the empirical formula for this compound? 57. A compound that contains only nitrogen and oxygen is 30.4% by mass of nitrogen. The molar mass of the compound is 92 grams/mole. What is the empirical formula? What is the molecular formula? 58. A sample of urea contains 1.1211 g N, 0.161 g H, 0.480 g C, and 0.640 g O. What is the empirical formula for this compound? If the compound is found to have a molecular weight of 180. g/mol, what is the molecular formula? 59. A compound containing only sulfur and nitrogen is 69.6% S by mass. It also has a molar mass of 184 g/mol. What are the empirical and molecular formulas? 60. Acrylic acid, used in the manufacture of plastic has a composition of 50.0% C, 5.60% H, and 44.4% O. The molar mass of the compound is 288 g/mol. What are the empirical and molecular formulas of this compound? 61. Over the years, the thermite reaction has been used for welding railroad rails, for incendiary (combustible) bombs, and to ignite solid fuel rocket motors. The reaction is: Fe2O3 (s) + 2 Al (s) 2 Fe (s) + Al2O3 (s) What mass of iron III oxide must be used to produce 515.0 g of iron? 62. The reusable booster rocket of the U.S. space shuttle employs a mixture of aluminum and ammonium perchlorate for fuel. A possible equation for the reaction is: 3 Al (s) + 3 NH4ClO4 (s) Al2O3 (s) + AlCl3 (s) + 3 NO (g) + 6 H2O What mass of aluminum must be used to produce 67 grams of AlCl3? 63. Alka-Seltzer uses the reaction of sodium bicarbonate with citric acid to produce a fizz. The reaction is: 3 NaHCO3 (aq) + C6H8O7 (aq) 3CO2 (g) + 3 H2O (l) + Na3C6H5O7 (aq) What mass of C6H8O7 must be used in the tablet to produce 1.558 g of CO2? 8 64. White phosphorus, P4, burned in excess oxygen forms diphosphorus pentaoxide, P 2O5. a. Write a balanced equation for the reaction that occurs (remember oxygen is O 2). b. How many grams of P2O5 are formed if 3.40 g of P4 react? c. How many grams of oxygen would be consumed using 16.00 g of P 4? 65. When a mixture of silver metal and sulfur is heated, silver sulfide is formed: 16 Ag (s) + S8 (s) 8 Ag2S (s) How many grams of Ag2S are produced if 2.00 g of silver reacts with 2.00 g of sulfur? 66. Aluminum burns in bromine to produce aluminum bromide: 2 Al (s) + 3 Br2 (l) 2 AlBr3 (s) In a certain experiment, 6.00 g of aluminum is burned in 24.0 g of bromine. What is the maximum amount of aluminum bromide that can be produced? 67. Acid-base neutralization reactions are very common in industrial processes. This is the reaction of sulfuric acid with sodium hydroxide: H2SO4 (aq) + 2 NaOH (aq) Na2SO4 (aq) + 2H2O (l) What is the maximum amount of Na2SO4 that can be produced if you use 26.5 g of H2SO4 and 25.4 g of NaOH? Some higher thinking problems… 68. Impure nickel can be purified by first forming the compound Ni(CO) 4, which is then decomposed by heating to yield very pure nickel. The metallic nickel in the sample reacts with carbon monoxide as follows: Ni (s) + 4 CO (g) Ni(CO)4 (s) The other metals in the ore do not react with carbon monoxide. If 94.2 g of a metal mixture produced 98.4 g of Ni(CO) 4 , what is the mass percent of nickel in the original sample? **The following are new problems. ☺ (SEE “Unknown CH/CHO Assistance Sheet”, and Sample Problem at end of packet) 69. Alcohols burn rapidly in oxygen. A chemist is burning an alcohol in an attempt to determine its identity. She knows the possibilities are: CH3OH, C2H5OH, C3H7OH, C4H9OH, or C5H11OH. In the combustion of 5.00 grams of an alcohol the chemist produced 11.89 grams of CO2 and 6.09 grams of H2O. What is the identity of the alcohol? 70. Many people take a little ascorbic acid every day to keep from getting sick (remember it’s vitamin C). The compound contains C, H, and O. During the combustion of 2.00 g of ascorbic acid, 3.09 g CO 2 and 0.818 g H2O are produced. What is the empirical formula for the compound? What is the molecular formula if the molar mass is found to be 176 g/mol? 71. Menthol, a strong smelling substance used in cough drops is a compound of carbon, hydrogen, and oxygen. When 15.96 grams menthol was subjected to combustion analysis, it produced 44.9 g CO 2 and 18.4 g H2O. The molecular weight of the compound is 156 g/mol. What is the molecular formula? 72. Hydrocarbons are compounds that contain only H and C. Most of these compounds are used as organic solvents or the building blocks of larger molecules. 7.00 g of one such hydrocarbon undergoes combustion and produces 23.69 g CO2 and 4.846 g H2O. What is the empirical formula for this hydrocarbon? What is the molecular formula if the molar mass is found to be 78 g/mol? (Remember only C and H). 73. The combustion of 10.0 g of a compound containing C, H, and O produced 20.0 g CO2 and 8.18 g H2O. What is the empirical formula? If the MW = 176 g/mol, what is the molecular formula? ACT Practice: The new AP Chemistry Exam is organized around six big ideas in chemistry. There is a focus on Inquiry-based learning. To better prepare yourself for this, it may be helpful to practice ACT passages. Please go to the following site and write your answers down on the paper. When you are done, check your answers and write down the corrected answer. You may “PRINT SCREEN” or “SNAPSHOT” and print the page instead. The more practice you get, the better you will perform on these questions. 74. http://www.highschooltestprep.com/act/science/practice-test-3/ 75. http://www.actstudent.org/sampletest/science/sci_06.html Below is a fabulous resource that you may want to set to as a “favorite”. There are many different practice problems for each chapter that we do. http://www.sciencegeek.net/APchemistry/APtaters/directory.shtml 9 Name____________________________ (DETACH FROM PACKET) 1- Charged Ions dihydrogen phosphate H2PO41hydrogen sulfite HSO31hydrogen sulfate HSO41bicarbonate HCO31(hydrogen carbonate) nitrite NO21nitrate NO31hypochlorite ClO1chlorite ClO21chlorate ClO31perchlorate ClO41cyanide CN1thiocyanate SCN1hydroxide OH11acetate C2H3O2 / CH3COO1permanganate MnO41bromate BrO3azide N3- POLYATOMIC IONS TO MEMORIZE 2- Charged Ions 3- Charged Ions hydrogen phosphate sulfite sulfate carbonate HPO42SO32SO42CO32- chromate dichromate silicate oxalate CrO42Cr2O72SiO32C2O42- phosphate phosphite borate PO43PO33BO33- ammonium NH4+ --------------------------------------------------------CUT HERE--------------------------------------------------------------- Solubility Rules for Common Ionic Compounds in Water ALL 1A elements, the ALKALI METALS, in compounds are soluble!!! *1 NO3All nitrates are soluble. C2H3O2- *2 All acetates are soluble. - *3 All chlorides are soluble. Exceptions: AgCl PbClX Hg2Cl2 Br - *3 All bromides are soluble. Exceptions: AgBr PbBrX HgBr2 - *3 All iodides are soluble. Exceptions: AgI PbIX HgI2 *4 All sulfates are soluble. Exceptions: Ag2SO4 PbSO4 Hg2SO4 BaSO4 CaSO4 SrSO4 Cl I SO4 2- Hg2Br2 Hg2I2 S2- All sulfides are insoluble. Soluble: Those of *61A, 2A elements and *5(NH4)2S CO32- All carbonates are insoluble. Soluble: Those of *61A elements and *5 (NH4)2CO3 PO43- All phosphates are insoluble. Soluble: Those of *61A elements and *5 (NH4)3PO4 OH - All hydroxides are insoluble. Soluble: Those of *61A elements and Ba(OH)2 Ca(OH)2 Sr(OH)2 Some tips on remembering some of these: (You’re on your own for the rest!) *1: “Knights can take on anything.” *2: “Aces can take on anything.” *3: “I ClobBer” can take on anything except silver, lead, and mercury. *4: Fat Sol or “Solfat” will eat anything except silver, lead, mercury, just BaCause Sir. *5: Got “Ammo”(ammonium), than you can take on just about anything! 10 A Nomenclature Tip Sheet Diatomics: H2 N2 O2 F2 Cl2 Br2 I2 Use the “Triple 7 Rule” or “H-I O-N F-Cl-Br” Molecular: The prefixes tell you how many, just write the formula and do not reduce. Ionic: If there is a metal, you must CRISS-CROSS ABSOLUTE-VALUE & REDUCE. Remember to put polyatomic ions in parentheses. Some of the polyatomic ion tips: 1. First of all, notice the bolded borders. These ions have been grouped according to similarities. 2. Compare PO4-3 to HPO4-2 to H2PO41-. Notice that each time you add a H+, the overall charge increases. (that’s what happens when you add + charges.) This works for others on the list. 3. Choosing –ite versus –ate: “After I –ate, I gained an O”. Notice that the –ate version contains an extra oxygen atom compared to the –ite. **Please also note, -ite and –ate do not tell how many O atoms, just whether there are more or less. 4. “Silly Kate rides a tricycle, not a bicycle”. Don’t ask!! Silicate has -O3. Many people incorrectly write SiO4. The charge is –2. 5. “A COw (or an OX) has 2 eyes and 4 legs.” Again, don’t ask. Oxalate is C2O42- (all evens.) 6. Have some “carbonated” COke in your car(3 letters); it’s better with 2 people: CO327. Night is the 3rd part of the day and there is one moon, so NO31- is nitrate. 8. Chromate: Chrome wheels come in 4’s and then think “24’s” CrO429. Nick the Camel ATE a Clam Supper in Phoenix **Use number of consonants & vowels Nitrate Carbonate Chlorate Sulfate Phosphate to determine #O & charge NO3CO32ClO3- SO42PO43- Example: Nick has 3 consonants and 1 vowel, so NO3- The –ite version is just one less oxygen, with the same charge I hope some of these help. You are on your own otherwise. ☺ 11 (DETACH FROM PACKET) Predicting Chemical Reactions Notes The products of a chemical reaction may often be predicted by applying known facts about common reaction types. While there are hundreds of different kinds of chemical reactions, only 5 general types of reactions will be considered: Combustion, Single Displacement, Double Displacement, Synthesis, and Decomposition (Analysis). Balancing Equations and Identifying Reactions Synthesis / Combination 2> smaller compounds/elements Decomposition (see below) 1 larger compound Combustion any reaction with O2 as a reactant Single Replacement “Football Substitution” AB + Double Replacement “Double Dating” AB + 1 larger compound >2 smaller compounds / elements B CD AC AD + + B CB A COMBUSTION REACTION occurs when an element/compound reacts with oxygen(O2), often producing energy in the form of heat/light. Ex: CH4 + 2 O2 CO2 + 2 H2O + heat/light **Hydrocarbons are compounds made up mainly of carbon and hydrogen (they also may contain oxygen or nitrogen). When hydrocarbons react with oxygen gas, they from CO2 + H2O **A rhyme to help you remember: “Reacting O2 with “CH or CHO” always produces “CO and HO”! A SINGLE DISPLACEMENT REACTION occurs when one element displaces another in a compound. The general form is: element + compound element + compound A + BC B + AC ex: Zn + 2HCl H2 + ZnCl2 We call this: “FOOTBALL SUBSTITUTION” A DOUBLE DISPLACEMENT REACTION occurs when the cations and anions of the two reactants are interchanged. The general form is: compound + compound compound + compound AB + CD AD + CB Ex: FeS + 2HCl FeCl2 + H2S We call this: “DOUBLE DATING” A SYNTHESIS REACTION occurs when two or more elements or compounds are combined to form ONE more complex substance. The general form is: element/compound + element/compound compound ex: Fe + S FeS A DECOMPOSITION (ANALYSIS) REACTION occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied. A compound may decompose to form simpler compounds and/or elements. The general form is: compound two or more substance. There are six general types: 1. Some oxy-acids, when heated, decompose to form water and the non-metal oxide. Ex: H2CO3 H2O + CO2 2. Some metallic hydroxides, when heated, decompose to form the metal oxide and water. Ex: Ca(OH)2 CaO + H2O 3. Some metallic carbonates, when heated, decompose to form the metal oxide and carbon dioxide. Ex: Li2CO3 Li2O + CO2 4. Some metallic chlorates, when heated, decompose to form the metal chloride and oxygen gas. Ex: 2KClO3 2KCl + 3O2 5. Most metallic oxides are stable, but a few decompose when heated to form the metal and oxygen gas. Ex: 2HgO 2Hg + O2 6. Some compounds may be decomposed by electricity, called electrolysis, into their elements. Ex: 2NaCl 2Na + Cl2 12 Unknown CH/CHO Assistance Sheet Before you begin the problem, analyze that you are solving for an EMPIRICAL and MOLECULAR FOR”MOL”A. So, you need to find “MOLES” of C, H, and O to get the answer. 1. Write the equation for the combustion reaction. Then, write the values given below each substance. 2. Find the %C in the CO2 and multiply this constant value (using the decimal form of the percent) by the total grams of CO2. Underline this value, #g C. Change #g C #moles C and underline your answer. Repeat this for the H in H2O. 3. Now, you have to deal with the oxygen. The problem is that the O appears in both of the reactants, making it hard to find exactly how much is only in the {CHO}, not in the O2. But, you know by the Law of Conservation of Mass how much C and H are in {CHO}, because the amount present in the products must be equal to what is present in the reactants and each of these only appear in one place on either side. You also were given the amount of {CHO} that you started with; the C+H+O = {CHO}! #grams of {CHO} - #grams C - #grams H = #grams O change #grams O #moles O 4. Write the for”MOL”a. Divide by the lowest number to get whole numbers greater than 1. This whole number, reduced ratio between the atoms is called the EMPIRICAL for”mol”a. 5. For the molecular for”mol”a, use the “ME” equation to find your “multiplier”: Molar mass of MOLECULAR FORMULA = Molar mass of EMPIRICAL FORMULA Multiply the empirical formula by this value to find the molecular formula. YOU ARE DONE!! Sample problem: Vanillin (methyl vanillin) is used in flavorings, fragrances, pharmaceuticals, and perfumes is made of carbon, hydrogen, and oxygen. If 3.00g of the substance is combusted and 6.93 grams of CO2 and 1.42 grams of water are produced, what is the empirical formula for the substance? The molar mass of the molecular formula is 456 g/mol. Find the molecular formula. AP Chemistry *may detach Name_______________________________ 13 Equations Guide Part 1 The following are optional ways to solve particular types of problems. Some are simple rules we will follow when solving problems. Molecular Weights Mass % (a.k.a. % composition or % by weight) Empirical Formula or “forMOLa” Empirical Formula -when masses of products are given (combustion process) **NEW Molecular Formula -when mass of compound and Empirical Formula are given Grams Moles Round atomic weights from the periodic table to the tenth's place. (units: g/mol) %X= grams of element X total molecular weight of compound Use the following steps. Start at the point of units that you are given. a. Change % to grams out of 100 grams b. Change grams moles (use periodic table) c. Write the chemical formula with moles (rounded to .01 place) as subscripts. d. Divide each mole value by the lowest number to achieve estimated whole number values. a. Calculate grams of each element: #g of product mole (MW) #g of element (MW) #g mole of product b. If the compound given contains oxygen, you need to subtract grams of each element from the total mass to find how much oxygen there is. c. Now you know grams of each element. Follow b-d under “Empirical Formula”. a. Calculate the total MW of the empirical formula. b. Divide the given mass of the compound by the MW of the empirical formula. c. Multiply the subscripts in the empirical formula by the unit calculated in b). # grams mole (Use P.T to find molecular weight in g/mol) (MW)# grams Moles Grams # moles Moles Molecules # moles 6.02 x 1023 molecules mole Molecules Moles # molecules mole 6.02 x 1023 molecules Stoichiometry There are three bridges (ratios) you can use when going from one chemical to another. They are M L M (not M & M ). These stand for: Moles Liters Molecules (MW)# grams mole (Use P.T to find molecular weight in g/mol) Example: Find molecules of A when you know grams of B # grams B mole # mol A 6.02 x 1023 molecules (MW)# grams B # mol B mol A (Note: in bold is the ratio of the formulas from the chemical equation.) Remember, the only time you can use 22.4 liters = 1 mole is for a gas at STP. 14