College Board References and Resources: Instructions: Al2O3 (s) Cu(s) Na+(aq) OH - (aq) H3O+(aq) NO3 (aq) CaO (s) K+(aq) MnO4 (aq) SO3 (g)

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1 College Board References and Resources: I have noted right the formulas/sections of the table of equations and constants that are pertinent to the Big Idea we are currently studying. Meaning that any mathematical procedures, constants, formulas, etc. not noted here, and used for the Big Idea, cannot be referenced during your AP examination. Instructions: Write the chemical symbol (including state to the best of your ability) for the following formulas. If the substance exists mainly as separate ions in solution, write the separate ions. Remember, on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question. 1. solid aluminum oxide Al2O3 (s) 2. a solution of sodium hydroxide Na + (aq) OH - (aq) 3. solid calcium oxide CaO (s) 4. sulfur trioxide gas SO3 (g) molar sulfuric acid 2H3O + (aq) SO4 2- (aq) molar potassium hydroxide K + (aq) OH (aq) 7. calcium metal Ca (s) 8. nitrogen gas N2 (g) 9. solid copper(ii) sulfide Cu2S (s) 10. oxygen gas O2 (g) 11. concentrated hydrochloric acid H3O + (aq) Cl (aq) 12. powdered manganese dioxide MnO2 (s) 13. concentrated solution of ammonia NH3 (aq) 14. a solution of zinc iodide Zn 2+ (aq) 2I (aq) 15. a solution of copper(ii) sulfate Cu 2+ (aq) SO4 2- (aq) 16. a solution of barium hydroxide Ba 2+ (aq) 2OH (aq) 17. a solution of magnesium nitrate Mg 2+ (aq) 2NO3 (aq) 18. solid lithium hydride LiH(s) 19. water H2O(l) 20. a solution of ammonium NH4 + (aq) OH (aq) 21. a solution of hydrofluoric acid HF(aq) 22. a piece of aluminum metal Al(s) 23. a solution of silver nitrate Ag + (aq) NO3 (aq) 24. a solution of potassium iodide K + (aq) I (aq) 25. solid potassium oxide 2K + (aq) O 2- (aq) 26. an excess of nitric acid solution H3O + (aq) NO3 (aq) 27. copper(ii) sulfate Cu 2+ (aq) SO4 2- (aq) 28. carbon dioxide gas CO2(g) 29. a suspension of calcium carbonate CaCO3 (aq) 30. a strip of copper Cu(s) 31. dilute nitric acid H3O + (aq) NO3 (aq) 32. potassium permanganate solution K + (aq) MnO4 (aq) 33. an acidic solution of hydrogen peroxide H3O + (aq) H2O2 (aq) 34. solid manganese (II) sulfide MnS(s) 35. chlorine gas Cl2 (g) 36. hot iron filings Fe (S) 37. solid magnesium nitride Mg3N2 (s) 38. sulfur dioxide gas SO2 (g) 39. a suspension of silver chloride AgCl (aq) 40. a solution of tri-potassium phosphate 3 K + (aq) PO4 3 (aq) 41. a solution of zinc nitrate Zn 2+ (aq) NO3 (aq) 42. sodium cyanide solution Na + (aq) CN (aq) 43. a solution of manganese(ii) sulfate Mn 2+ (aq) SO4 2- (aq) 44. a solution of ammonium sulfide 2NH4 + (aq) S 2- (aq) 45. phosphorus(v) oxide powder P2O5 (s) 46. solid ammonium carbonate (NH4)2CO3 (s) 47. solid potassium permanganate KMnO4 (s) 48. a small piece of sodium metal Na (s) 49. a solution of potassium dichromate 2K + (aq) Cr2O7 2- (aq) 50. an acidified solution of iron(ii) chloride H3O + (aq) Fe 2+ (aq) 2Cl aq) 51. Methane CH4 (g) 52. solid barium oxide BaO (s) 53. a solution of iron(ii) nitrate Fe 2+ (aq) NO3 (aq) 54. solid calcium phosphate Ca3(PO4)2 (s) 55. hydrogen sulfide gas H2S (g) 56. a solution of mercury(ii) chloride Hg2 2+ (aq) 2Cl (aq) 57. solid calcium hydride CaH2 (s) 58. a bar of zinc metal Zn (s)

2 Instructions: Write net-ionic equations for these double replacement reactions. I should not have to tell you that they need to be balanced and states indicated. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question. 59. Aqueous solutions of zinc sulfate and sodium phosphate are mixed. We can only hope for the uncomplicated precipitation reaction. 3Zn 2+ (aq) + 2PO4 3 (aq) Zn3(PO4)2 (s) 60. Hydrofluoric acid is combined with a solution of lead(ii) nitrate. Anytime we see acid, we know it is in solution, but we must decide if the acid is strong or weak. Remember to write weak acids as molecules (and strong acids as ions, and possibly the anion might be a spectator and drop out of the reaction). Fluorides are not particularly soluble compounds. 2HF(aq) + Pb 2+ (aq) PbF2(s) + 2H + (aq) 61. Solid calcium sulfide is sprinkled into dilute hydrochloric acid. Dihydrogen sulfide, while it is an acid, in large part it will form a gas and drive the reaction forward. Crystals/solid/ powdered all refer to a compound that should not be dissociated. CaS(s) + 2H + (aq) H2S(aq) + Ca 2+ (aq) 62. An aqueous solution of lead(ii) acetate reacts with hydrochloric acid. Lead ions precipitate with most everything except, except nitrates and acetates. Don t forget that weak acids should be represented as molecules, not ions. Pb 2+ (aq) + 2C2H3O2 (aq) + 2H + (aq) + 2Cl (aq) PbCl2(aq) + 2HC2H3O2(aq) 63. Solid sodium carbonate is stirred into hydrobromic acid. Remember that whenever carbonic acid shows up as a product, it is a phantom, decompose it. 2H + (aq) + Na2CO3 (s) ( H2CO3) H2O (l) + CO2(g) + 2Na + (aq) 64. Nitric acid is reacted with an aqueous solution of calcium acetate. Watch for the formation of molecular weak acids - they may show up on the product side. H + (aq) + C2H3O2 (aq) HC2H3O2 (aq) 65. Hydrochloric acid is poured over powdered potassium carbonate. Watch for the word solid... and don t forget the decomposing carbonic acid. 2H + (aq) + K2CO3(s) ( H2CO3) CO2(g) + H2O(l) + 2K + (aq) 66. An aqueous solution of cadmium chloride is reacted with an aqueous solution of potassium phosphate. Whew, thank goodness for an uncomplicated precipitation reaction. 3Cd 2+ (aq) + 2PO4 3 (aq) Cd3(PO4)2(s) 67. A solution of hydrofluoric acid is poured over barium carbonate crystals. Remember that fluoride salts are often insoluble, weak acids should be represented as molecules, watch for the phantom the carbonic acid that decomposes. 2HF(aq) + BaCO3(s) H2O(l) + CO2(g) + BaF2(s) 68. Hydroiodic acid is poured over potassium sulfite. Since it does not say solution of potassium sulfite and the acid is poured over, the implication is the potassium sulfite is solid. Watch out for yet another phantom, sulfurous acid. Just like carbonic acid, it too will decompose when formed. 2H + (aq) + K2SO3(s) ( H2SO3) H2O(l) + SO2(g) + 2K + (aq) 69. An aqueous solution of barium hydroxide is reacted with an aqueous solution of iron(iii) sulfate. Beware of the rarely occurring, but actually possible, double precipitate reaction! AP would not hold you responsible for knowing that barium sulfate is insoluble. There would be some hint given in the problem. 3Ba 2+ (aq) + 6OH (aq) + 2Fe 3+ (aq) + 3SO4 2 (aq) 3BaSO4(s) + 2Fe(OH)3(s) 70. A solution of sodium hydroxide is poured into a solution of magnesium chloride. Yippee! another uncomplicated precipitation reaction. We know that magnesium hydroxide is quite insoluble from our Milk of Magnesia demonstration. 2OH (aq) + Mg 2+ (aq) Mg(OH)2(s) 71. Aqueous lead(ii) nitrate is combined with potassium iodide Yeah, one of your favorites, a very yellow, precipitation reaction. 2I (aq) + Pb 2+ (aq) PbI2(s) Instructions: Write net-ionic equations for these acid-base reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question. 73. A 0.40 M solution of acetic acid is reacted with a 0.20 M lithium hydroxide solution Pay close attention to whether or not you are working with strong or weak acids and remember that acetic acid is a weak acid and must be written as a molecule. HC2H3O2(aq) + OH (aq) H2O(l) + C2H3O2 (aq) 74. A solution of nitric acid is combined with a suspension of magnesium hydroxide. Remember to check the solubility of magnesium hydroxide but the very fact that it says suspension, you are being told solid particles. 2H + (aq) + Mg(OH)2(aq) 2H2O(l) + Mg 2+ (aq)

3 75. A solution of sulfuric acid is poured over copper(i) hydroxide crystals Remember that copper(i) hydroxide crystals must be written as a compound. Sulfuric acid is a strong acid. The reaction after splitting up the ionized species would be: 2H + (aq) + SO4 2 (aq) + 2CuOH(s) 2H2O(l) + 2Cu + (aq) + SO4 2 (aq) Then after eliminating the sulfate spectator ion would be: 2H + (aq) + 2CuOH(s) 2H2O(l) + 2Cu + (aq) and then this would need to be reduced to whole number ratios since the directions request this, and a net ionic equation should be the same whether the acid used were H2SO4 or HNO3. H + (aq) + CuOH(s) H2O(l) + Cu + (aq) 76. A solution of sulfuric acid is added to a solution of barium hydroxide until the same number of moles of each compound has been added. Pay close attention to whether or not you are working with strong or weak acids and bases, and be on the lookout for any precipitates that may form during the neutralization. In this case, until the same number of moles of each compound has been added is a distractor and does not change how you would write the reaction. H + (aq) + SO4 2 (aq) + Ba 2+ (aq) + OH (aq) H2O(l) + BaSO4(s) 77. Hydrogen sulfide gas is bubbled through a solution of potassium hydroxide. Remember that gases are always written as molecular species, which means that any ions that result from them may not be eliminated as spectator ions. H2S(g) + 2 OH (aq) 2H2O(l) + S 2 (aq) 78. A solution of sodium hydroxide is added to a solution of sodium dihydrogen phosphate until the same number of moles of each compound has been added. Remember that the dihydrogen phosphate ion has just that; two hydrogens attached to the phosphate ion. OH (aq) + H2PO4 (aq) H2O(l) + HPO4 2 (aq) 79. Equal volumes of 0.1-molar sulfuric acid and 0.1-molar potassium hydroxide are mixed. We can only hope that you get a simple strong acid/strong base combination on the AP exam. H + (aq) + OH (aq) H2O(l) 80. Excess potassium hydroxide solution is added to a solution of potassium hydrogen phosphate Hydrogen phosphate, in contrast to dihydrogen phosphate has only one hydrogen attached to the phosphate ion OH (aq) + HPO4 2 (aq) H2O(l) + PO4 3 (aq) 81. Excess hydrochloric acid solution is added to a solution of sodium dihydrogen phosphate In this case acid, H + ions, is added to dihydrogen phosphate, which will form the weak acid, which can be present as molecules in solution. The same reaction would occur if the acid were added to the monohydrogen phosphate ion. H + (aq) + HPO4 2 (aq) H2PO4 (aq) H + (aq) + H2PO4 (aq) H3PO4(aq) (or push even further to H3PO4, AP would likely accept either answer) M ammonia reacts with 0.2 M hydrobromic acid. Ammonia is a molecular compound that acts as a base accepting a proton (H+). Remember your strong acids. NH3(aq) + H + (aq) NH4 + (aq) 83. A solution of ammonia is added to a dilute solution of acetic acid. Ammonia is a molecular compound that acts as a base accepting a proton (H+). Don t forget that acetic acid is a weak acid. NH3(aq) + HC2H3O2(aq) NH4 + (aq) + C2H3O2 (aq) 84. A solution of ammonia and hydrofluoric acid are combined. Watch out for weak acids and bases, remember that they must be written as molecules not ions. NH3(aq) + HF(aq) NH4 + (aq) + F (aq) Instructions: Write net-ionic equations for these single replacement reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question. 85. A strip of magnesium is added to a solution of silver nitrate The magnesium will replace the silver in solution. Remember to leave out the spectator ions. Mg(s) + 2Ag + (aq) Mg 2+ (aq) + 2Ag(s) 86. Aluminum metal is dropped into an solution of zinc chloride Remember that zinc always forms 2+ charge. Be sure and eliminate spectator ions, and remember that charge must also balance. 2Al(s) + 3Zn 2+ (aq) 3Zn(s) + 2Al 3+ (aq) 87. Solid silver is dropped into an solution of gold(ii) nitrate Be sure and eliminate spectator ions, and remember that charge must also balance. 2Ag(s) + Au 2+ (aq) Au(s) + 2Ag + (aq) 88. Aluminum foil is dropped into a solution of nitric acid. When hydrogens are replaced, and take their electron back they must leave as a diatomic molecule. 2Al(s) + 6H + (aq) 2Al 3+ (aq) + 3H2(g) 89. Solid barium is added to chlorous acid Be alert for weak acids which must be written as molecules. Ba(s) + 2HClO2(aq) Ba 2+ (aq) + H2(g) + 2 ClO2 (aq) 90. Potassium metal is dropped into water When alkali metals replace hydrogen in water, it might be easier to remember the products if you think of water as HOH, and it is the first H+ that is what is being replaced, this is why sodium hydroxide is a product, not sodium oxide. 2K(s) + 2H2O(l) 2K + (aq) + 2OH (aq) + H2(g)

4 91. Chromium(II) nitrate solution is combined with iron(iii) nitrate solution. At first it might appear as if nothing would happen, but a reaction will always happen on the AP exam questions. Since there can not be any precipitation formation, and it clearly is not an acid base reaction, can think single replacement. Remember that one element must be oxidized while another is reduced. Cr 2+ (aq) + Fe 3+ (aq) Cr 3+ (aq) + Fe 2+ (aq) 3 Cr 2+ (aq) + 2 Fe 3+ (aq) 3 Cr 3+ (aq) + 2 Fe(s) OR 92. Iron(II) nitrate solution is mixed with cobalt(iii) chloride solution This is the same type of reaction as #90 Fe 2+ (aq) + Co 3+ (aq) Fe 3+ (aq) + Co 2+ (aq) 93. Liquid bromine is added to an aqueous sodium iodide solution Halogens can replace each other. Their reactivity follows their order within their family on the periodic table. Br2(l) + I (aq) I2(s) + Br (aq) 94. Hydrogen gas is passed over hot copper(ii) oxide. In this reaction that should look like a single replacement, the hydrogen is more likely to behave as a positive ion, thus it will replace the copper not the oxygen. H2(g) + CuO(s) H2O(l) + Cu(s) 95. Small chunks of solid sodium is added to water. This is analogous to #90 2Na(s) + 2H2O(l) 2Na + (aq) + 2OH (aq) + H2(g) 96. Magnesium metal is added to a dilute solution of nitric acid. This is analogous to #88 Mg(s) + 2H + (aq) Mg 2+ (aq) + H2(g) 97. Chlorine gas is bubbled into a solution of potassium iodide. This is analogous to #93 Cl2(g) + I (aq) I2 (s) + Cl (aq) Instructions: Write net-ionic equations for these decomposition reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question. 98. A 27 % hydrogen peroxide solution is catalytically decomposed This is a memorize, you must know this reaction. Do not get fooled into thinking that hydrogen gas is formed it is not. Remember, in case they ask the oxygen in peroxides always have a 1 oxidation state. 2H2O2(aq) O2(g) + 2H2O(l) 99. Solid potassium chlorate is heated in the presence of a catalyst Also a memorize metal chlorates always turn into metal chlorides and oxygen gas. 2KClO3(s) 2KCl(s) + 3O2(g) 100. Solid magnesium carbonate is heated. Memorize metal carbonates turn into metal oxides and carbon dioxide. MgCO3(s) MgO(s) + CO2(g) 102. Solid ammonium carbonate is heated. This is a tricky one. It is one of the phantoms. Since you should have memorized that carbonates decompose to carbon dioxide, you can assume that we get CO2 here as well, then you d be left with (NH4)2O (not an actual compound)...dissect that to get your friend ammonia, and voila, you are left with water as well. (NH4)2CO3(s) 2NH3(g) + 2H2O(l) + CO2(g) 103. Calcium sulfite is heated in a vacuum. This is probably not worth memorizing, just think in an analogous way to the carbonate decomposition... CaSO3 (s) 2CaO(s) + SO2(g) Instructions: Write net-ionic equations for these synthesis reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question Bromine vapor is passed over cadmium powder. With synthesis reactions, there isn t too much to think about, just slam it all together and build the most likely compound. Make sure you check the charges. Br2(g) + Cd(s) CdBr2(s) 105. Chlorine gas is reacted with aluminum. Remember the order, we write metals first in ionic compounds. 3Cl2(g) + 2Al(s) 2AlCl3(s) 106. Strontium oxide is reacted with sulfur trioxide. The tricky part is recognizing that it is a synthesis that you have in front of you. SrO(s) + SO3 (g) SrSO4 (s) 107. Hot bromine vapor is reacted with aluminum foil More of the same, just watch your charges. 3Br2(g) + 2Al(s) 2AlBr3(s)

5 108. The gases boron trifluoride and ammonia are mixed. This is one of AP s favorite synthesis reaction. It is actually a Lewis acid/base reaction. We will look at it a bit more closely in our acid base unit. BF3(g) + NH3(g) BF3NH3(aq) 109. A mixture of solid calcium oxide and solid tetraphosphorus decoxide is heated. In what appears to be a synthesis and you are wondering should you make phosphate or phosphite? go with the one in which the oxidation number of the P does not change. In this case, the phosphorus is maintaining its +5 oxidation state. No one else changes their oxidation numbers either. CaO(s) + P4O10(s) Ca3(PO4)2(s) 110. Calcium metal is heated strongly in nitrogen gas. Don t forget your charges. Ca(s) + N2(g) Ca3N2(s) 111. Magnesium ribbon is burned in oxygen. Certainly you ve seen this reaction so many times. 2Mg(s) + O2(g) 2MgO(s) 112. Powdered magnesium oxide is added to a container of carbon dioxide gas. This is the carbonate decomposition, backwards. If you learn your decomp reactions, you can often think of them in reverse as a synthesis. MgO(s) + CO2(g) MgCO3(s) Instructions: Write net-ionic equations for these combustion reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question Pentane is burned in oxygen The challenge with the combustion reactions is knowing the formula of what they are asking you to combust. But in all likelihood, it will not be too tough. Use Notes to review organic nomenclature. C5H12(g) + 8O2(g) 5CO2(g) + 6H2O(g) 114. Propene is burned in air Remember that combustion of all CH, or CHO compounds produce carbon dioxide and water. Assume complete combustion. 2C3H6(g) + 9O2(g) 6H2O(l) + 6CO2(g) 115. Butene is burned in air. Routine, if you can come up with the formula of the reactant. Learn your organic prefixes. C4H8(g) + 6O2(g) 4CO2(g) + 4H2O(aq) 116. Ethanol is burned in air. Learn your organic prefixes, sketch it our, add OH (for alcohol) on one end and fill in with the H s C2H5OH(l) + 3O2(g) 2CO2(g) + 3H2O(g) 117. Pentanol is combusted in air Pentanol = 5 carbons and an OH for the alcohol, fill in with the rest of H s to count up how many 2C5H11OH(l) + 15O2(g) 10CO2(g) + 12H2O(g) 118. Lithium metal is burned in air. Burning metals make the metal oxide only. 4Li(s) + O2(g) 2Li2O(s) 119. Gaseous diborane, B2H6, is burned in excess oxygen. Since CH compounds make carbon dioxide and water, assume the boron compound makes the appropriate boron oxide compound and water. Since boron is in the aluminum column, assume it combines in the same way aluminum would. B2H6 (g) + 3O2 (g) B2O3 (g) + 3H2O(g) 120. Carbon disulfide vapor is burned in excess oxygen. When elements other than metals or carbon, hydrogen, and oxygen show up just turn them into dioxides. CS2 (g) + 2O2 (g) CO2 (g) + 2SO2 (g) 121. Solid copper(ii) sulfide is heated strongly in oxygen gas. Metals make metal oxides, other elements make dioxides. 2CuS(s) + 3O2(g) 2CuO(s) + 2SO2(g) 122. Gaseous silane (silicon tetrahydride) is burned in oxygen A variation on the same theme, nonmetal dioxide and water. SiH4(g) + 2O2(g) SiO2(g) + 2H2O(g) 123. Propanol is burning in oxygen. Learn those organic prefixes. C3H7OH(l) + 5O2(g) 3CO2(g) + 4H2O(g) 124. Zinc sulfide is heated in an excess of oxygen. Again, metal oxide and nonmetal dioxide. 2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g)

6 Instructions: Write net-ionic equations for these anhydride reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question Sodium oxide powder is sprinkled in water. Metal oxides in water always turn into hydroxides. (Metal oxides are called basic anhydrides.) Don t forget to write substances that are substantially ionized as separate ions. Na2O(s) + H2O(l) 2Na + (aq) + 2OH (aq) 126. Dinitrogen pentoxide is bubbled through water. Nonmetal oxides in water make acids, these nonmetal oxides are called acid anhydrides. Which acid forms, you ask? Make the acid that will maintain the same oxidation number in the nonmetal. In this reaction, the oxidation number of nitrogen is +5 as a reactant and as a product. Don t forget to write the strong acid as separated ions. N2O5(g) + H2O(l) 2H + (aq) + 2NO3 (aq) 127. Dinitrogen trioxide gas is bubbled into water. Note that the nitrous acid is formed because of the +3 oxidation state of nitrogen. N2O3(g) + H2O(l) 2HNO2(aq) 128. Diphosphorus pentoxide is bubbled through water. Another acid anhydride. P2O5(g) + 3H2O(l) 2H3PO4(aq) 129. Rubidium hydride is placed into distilled water Metal hydrides (compounds in which hydrogen has an oxidation state of 1) combined with water always turn into metal hydroxides and hydrogen gas. Don t forget that soluble ionic compounds, such as the rubidium hydroxide must be written as separated ions. RbH(s) + H2O(l) Rb + (aq) + OH (aq) + H2(g) 130. Solid copper(ii) hydride is dropped into water Another metal hydride, but this time the hydroxide that is formed, copper (II) hydroxide is insoluble. Note that copper maintains the same oxidation state. CuH2(s) + 2H2O(l) Cu(OH)2(s) + 2H2(g) 131. Solid strontium hydride reacts with hydrochloric acid Consider first what a hydride does in water (since hydrochloric acid is a solution, made with water), thus turns into a hydroxide then consider what that hydroxide will do in acid neutralize and make water, this makes water drop SrH2(s) + 2H + (aq) Sr 2+ (aq) + 2H2(g) 132. Powdered barium oxide is stirred into aqueous hydrochloric acid. Remember that in #130 and #131, the hydrochloric acid is a strong acid and must be written as ionized, and the resulting soluble metal chloride product makes the chloride end up as a spectator ion, and must be dropped out of the reaction. BaO(s) + 2H + (aq) Ba 2+ (aq) + H2O(l) 133. Solid potassium oxide is added to water. Another metal oxide in water basic anhydride. K2O(s) + H2O(l) 2K + (aq) + 2OH (aq) 134. Sulfur dioxide is bubbled through a dilute solution of sodium hydroxide. This is a two-for-one reaction. The sulfur dioxide reacts as an acid anhydride, making the appropriate acid, but then it neutralizes with the soluble base. Remember the sulfur maintains its same oxidation state, +4. SO2(g) + OH (aq) H2O(l) + SO3 2 (aq) 135. Gaseous sulfur dioxide bubbled through an aqueous solution of calcium hydroxide. This is the same as the previous reaction, however, the calcium combines to make an insoluble precipitate of alcium sulfite most sulfites (except for alkali sulfites) will be insoluble. SO2(g) + Ca 2+ (aq) + OH (aq) H2O(l) + CaSO3(s) M hydrochloric acid is poured over calcium oxide powder. Strong acid and an metal oxide, another two-for-one reactions. First the formation of the metal hydroxide in the water part of the hydrochloric acid solution, then the neutralization of that hydroxide. H + (aq) + CaO(s) H2O(l) + Ca 2+ (aq) 137. Ammonia and carbon dioxide gases are bubbled into cold distilled water. This seems like a contradiction to Decomp #4 reaction (also listed as a phantom ) however, a reaction must occur (or it would not be on the test), and perhaps the cold water helps keep the formation back into gases so just assume that it is the reverse reaction, and the formation of the ions. NH3(aq) + CO2(g) + H2O(l) NH4 + + CO3 2 (aq) 138. Solid phosphorus pentachloride is added to excess water. This is a tough reaction and is not likely to end up on the AP exam... but check it out on the notes. 2PCl5(s) + 8H2O(l) 2H3PO4(aq) + 10H + (aq) + 10Cl (aq) Instructions: Write net-ionic equations for these complex-ion reactions. Remember that on the AP exam you may only use the periodic table. No solubility chart. However much information will be embedded in the question Concentrated ammonia is is added to a solution of zinc chloride The term concentrated is a hint that a complex ion will be formed. How many ligands should you place around the positive metal ion? Although each metal has a very particular amount that it usually binds with, AP is likely to allow most any amount between 2 6, as long as you show the appropriate charge. Since ammonia is neutral, the same charge on zinc, 2+, is the charge of the complex ion. 4NH3 + Zn 2+ [Zn(NH3)4] 2+

7 140. A solution of aluminum chloride is reacted with excess, concentrated sodium hydroxide The terms excess and concentrated are screaming at you to make the aluminate complex ion. While it is true that aluminum takes 4 ligands, resulting in a complex ion with a 1 charge. (If you were to place 6 OH ions around the Al 3+ ion, resulting in a 3 complex ion, you would still get credit.) Al 3+ (aq) + 4OH (aq) [Al(OH)4] (aq) 141. An excess of nitric acid solution is added to a solution of tetraaminecopper(ii) sulfate. Since ammonia is a weak base, the addition of acid will drag the ammonia off the copper complex to react and produce the ammonium ion. 4H + (aq) + [Cu(NH3)4] 2+ (aq) Cu 2+ (aq) + 4NH4 + (aq) 142. A solution of diamminesilver(i) chloride is treated with dilute hydrochloric. Again, the acid pulls the ammonia off the complex ion, and a silver chloride precipitate will result. 2H + (aq) + Cl (aq) + [Ag(NH3)2] 2+ (aq) AgCl(s) + 2NH4 + (aq) 143. Excess concentrated ammonia solution is added to a suspension of silver chloride. Ammonia is able to replace the Cl in the solid silver chloride and produce a complex ion that will be soluble 2NH3(aq) + AgCl(aq) [Ag(NH3)2] + (aq) + Cl (aq) 144. A suspension of zinc hydroxide is treated with concentrated sodium hydroxide solution. Again, the term concentrated is screaming at you to make a complex ion. Again the exact amount of OH ligands that you put with the zinc is not so important, but the resulting charge on the complex ion must be represented correctly. Zn(OH)2 (aq) + 2OH (aq) [Zn(OH)4] 2 (aq) 145. Excess sodium cyanide is added to a solution of silver nitrate. In AP speak, the term excess is code for complex ion! Just be sure the number of CN ligands you attach results in the correct charge on the complex ion. Ag + (aq) + 2CN (aq) [Ag(CN)2] (aq) 146. A concentrated solution of ammonia is added to a suspension of zinc hydroxide. The term concentration solution, is again telling you to make a complex ion, and the term suspension is telling you to write the zinc hydroxide as a solid, and not as separate ions. 4NH3(aq) + Zn(OH)2(aq) [Zn(NH3)4] 2+ (aq) + 2OH (aq) 147. An aqueous solution of hydrochloric acid is added to a solution containing the tetraaminecadmium(ii) ion. This is analogous to #141 above 4H + (aq) + [Cd(NH3)4] 2+ (aq) Cd 2+ (aq) + NH4 + (aq) Instructions: Determine the oxidation number of each element in the following ions or compounds: 148. BrO3 Br +5 O CaH2 Ca +2 H C2O4 2 C +3 O H4SiO4 H +1 Si +4 O F2 F SO4 2 S +6 O SF6 S +6 F N2O4 N +4 O H2AsO4 H +1 As +5 O PCl4 + P +5 Cl UO2 + U +5 O XeO4 2 Xe +6 O -2 Instructions: Using whichever method works best for you, balance the following oxidation/reduction reactions Balance the following net ionic Redox reactions in acidic solution: a. MnO4 + Cl Mn 2+ + Cl2 16H + (aq) + 2MnO4 (aq) + 10Cl (aq) 2Mn 2+ (aq) + 5Cl2(g) + 8H2O(l) b. Cu + SO4 2 SO2(g) + Cu 2+ 4H + (aq) + Cu(s) + SO4 2 (aq) SO2(g) + Cu 2+ (aq) + 2H2O(l) c. Pb + PbO2 + SO4 2 PbSO4 4H + (aq) + Pb(s) + PbO2(s) + 2SO4 2 (aq) 2PbSO4(s) + 2H2O(l) d. MnO2 + PbO2 MnO4 + Pb 2+ 4H + (aq) + 2MnO2(s) + 3PbO2 (s) 2MnO4 (aq) + 3Pb 2+ (aq) + 2H2O(aq) e. Br2 + SO2 Br + SO4 2 2H2O (l) + Br2 (l) + SO2 (g) 2Br (aq) + SO4 2 (aq) + 4H + (aq) f. P4(s) + NO3 H3PO4(aq) + NO(g) 8H2O(l) + 20 H + (aq) + 3P4(s) + 20 NO3 (aq) 12H3PO4(aq) + 20NO(g) g. Cr2O7 2 + CH3OH Cr 3+ + CH2O 8H + (aq) + Cr2O7 2 (aq) + 3CH3OH(l) 2Cr 3+ (aq) + 3CH2O(l) + 7H2O(l) h. NO3 + Fe Fe 2+ + NH4 + 10H + (aq) + NO3 (aq) + 4Fe(s) 4Fe 2+ (aq) + NH4 + (aq) + 3H2O(l) i. CuS + NO3 Cu 2+ + S(s) + NO(g) 8H + (aq) + 3CuS(s) + 2NO3 (aq) 3Cu 2+ (aq) + 3S(s) + 2NO(g) + 4H2O(aq) j. H2S + Fe 3+ FeS + S(s) 3H2S(aq) + 2Fe 3+ (aq) 2FeS(s) + S(s) + 6H + (aq)

8 161. Balance the following net ionic Redox reactions in basic solution: a. MnO4 + BrO3 MnO2 + BrO4 H2O(l) + 2MnO4 (aq) + 3BrO3 (aq) 2MnO2(s) + 3BrO4 (aq) + 2OH (aq) b. Bi(OH)3 + SnO2 2 Bi(s) + SnO3 2 2Bi(OH)3(s) + 3SnO2 2 (aq) 2Bi(s) + 3SnO3 2 (aq) + 3H2O(l) c. MnO4 + C2O4 2 MnO2 + CO3 2 4OH (aq) + 2MnO4 (aq) + 3C2O4 2 2MnO2(s) + 6CO3 2 (aq) + 2H2O(l) d. Pb 2+ + OCl PbO2 + Cl 2OH (aq) + Pb 2+ (aq) + OCl (aq) PbO2(s) + Cl (aq) + H2O(l) e. Bi(OH)2 + Sn(OH)3 Bi + Sn(OH)6 2 OH (aq) + Bi(OH)2(s) + Sn(OH)3 (aq) Bi(s) + Sn(OH)6 2 (aq) f. Zn + NO3 NH3(aq) + Zn(OH)4 2 6H2O(l) + 7OH (aq) + 4 Zn(s) + NO3+(aq) NH3(aq) + 4Zn(OH)4 2 (aq) g. Al + OH Al(OH)4 + H2 6H2O(l) + 2Al(s) + 2OH (aq) 2Al(OH)4 (aq) + 3H2(g) h. H2O2 + I IO3 + H2O 3H2O2(aq) + I (aq) IO3 (aq) + 3H2O(l) i. Fe(CN)6 3 + Re Fe(CN)6 4 + ReO4 8OH (aq) + 7Fe(CN)6 3 (aq) + Re(s) 7Fe(CN)6 4 (aq) + ReO4 (aq) + 4H2O(l) j. SO3 2 + Cl2 SO4 2 + Cl 2OH (aq) + SO3 2 (aq) + Cl2(g) SO4 2 (aq) + 2Cl (aq) + 2H2O(l) 119. All of the equations in the chart right are written as reductions (oxidations/reductions) The chemicals at the upper left (Cl2 and O2) are the most likely to be reduced (oxidized/reduced) and therefore the best oxidizing agents (oxidizing agents/reducing agents) The chemicals at the lower right (Na and K) are the most likely to be oxidized (oxidized/reduced) and therefore the best reducing agents (oxidizing agents/reducing agents) In an electrolytic cell, the (-) electrode is negative because it has too many (too many/too few) electrons. Chemicals that come into contact with the (-) electrode will gain (gain/lose) electrons and be reduced (oxidized/reduced). The (-) electrode in electrolysis is called the cathod (cathode/anode) Write the change that water goes through at the (+) electrode: 2H2O(l) + 2e H2(g) + 2OH (aq) 124. In an electrochemical cell, the (+) electrode is positive because is has too few (too many/too few) electrons. Chemicals that come into contact with the (+) electrode will lose (gain/lose) electrons and be oxidized (oxidized/reduced). The (+) electrode in electrolysis is called the anode (cathode/anode) Write the change that water goes through at the (-) electrode: 2H2O(l) O2(g) + 4H + (aq) + 4 e 126. Add these two reactions (123. and 125.) together (make certain the electrons cancel) and write the overall reaction for the electrolysis of water. 2H2O(l) 2H2(g) + O2(g) 127. We will perform this electrolysis using an aqueous solution of sodium sulfate. Both the Na + and H2O will be near the (-) electrode. Which chemical is more likely to be reduced? H2O E 0 Na+ = V < E 0 H20 = V 128. Both the SO4 2c and H2O will be near the (+) electrode. Which chemical will be oxidized? H2O SO4 2- cannot oxidize any further!!!!! 129. In the electrolysis of KI(aq) Both the K + and H2O will be near the (-) electrode. Which chemical is more likely to be reduced? H2O Both the I and H2O will be near the (+) electrode. Which chemical is more likely to be oxidized? I Write the reactions at each electrode and the overall reaction: E 0 K+ = V < E 0 H20 = V E 0 I = V > E 0 H20 = V Cathode: Anode: Overall: 2H2O(l) + 2e H2(g) + 2OH (aq) 2I (aq) I2(s) + 2e 2H2O(l) + 2I (aq) H2(g) + I2(s) + 2OH (aq)

9 130. In the electrolysis of CuSO4(aq) Both the Cu 2+ and H2O will be near the (-) electrode. Which chemical will be reduced? Cu 2+ Both the SO4 2 and H2O will be near the (+) electrode. Which chemical will be oxidized? H2O Write the reactions at each electrode and the overall reaction: E 0 Cu2+ = V > E 0 H20 = V SO4 2- cannot oxidize any further!!!!! Cathode: Anode: Cu 2+ (aq) + 2e Cu(s) 2H2O(l) O2(g) + 4H + (aq) + 4 e Overall: 2H2O(l) + 2Cu 2+ (aq) O2(g) + 4H + (aq) + 2Cu(s) 131. Silver plating occurs when electrolysis of a Ag2SO4 solution is used because silver metal is formed at the cathode (cathode/anode). This is the ( ) ( + / - )electrode. The reaction at this electrode is: Ag + (aq) + e Ag(s) Recall that 1 amp sec = 1 Coulomb and 96,500 Coulombs = 1 mole e s (Faraday s constant). If a cell is run for 200. seconds with a current of amps, how many grams of Ag will be deposited? 200. s amps 1 C 1 mol e 1 mol Ag g Ag = g Ag 1 amps s C 1 mol e 1 mol Ag 132. A current of 10.0 amperes flows for 2.00 hours through an electrolytic cell containing a molten salt of metal X. This results in the decomposition of mole of metal X at the cathode. The oxidation state of X in the molten salt is X 3+ (X +, X 2+, X 3+, X 4+ ) 10.0 amps 2.00 hrs 3600 s 1 C 1 mol e = mol e - = 3 e 1 hr 1 amps s C mol 133. Solutions of Ag +, Cu 2+, Fe 3+ and Ti 4+ are electrolyzed with a constant current until 0.10 mol of metal is deposited. Which will require the greatest length of time? Ti 4+ Most e -