3.2 COMBUSTION, SYNTHESIS, AND DECOMPOSITION REACTIONS

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1 3.2 COMBUSTION, SYNTHESIS, AND DECOMPOSITION REACTIONS (Page 117) 1. Reactants: a substance for fuel, and oxygen; conditions: three things must be present - fuel, oxygen, and heat; products: common oxides of the elements making up the substance that is burned. 2. CO 2(g) ; H 2 ; SO 2(g) ; NO 2(g) ; Fe 2 O 3(s) 3. Carbon dioxide and water are products of the combustion of carbon compounds that have had a significant effect on the atmosphere, including making it warmer than it would otherwise be. This phenomenon is known as the greenhouse effect. Gaseous oxides of nitrogen and sulfur are released from sources such as automobiles and coal-burning power plants. These oxides join the naturally produced oxides in the atmosphere, react with water vapour to form acids, and are responsible for the increased acidity of precipitation known as acid rain. (Page 121) 4. (a) Decomposition the product is a simpler elemental compound and an element. (b) Synthesis the product is a more complex compound. (c) Synthesis the product is a more complex compound. 5. (a) 2 Al (s) + 3 F 2(g) 2 AlF 3(s) synthesis (b) 2 KCl (s) 2 K (s) + Cl 2(g) decomposition (c) S 8(s) + 8 O 2(g) 8 SO 2(g) synthesis (combustion) (d) CH 4(g) + 2 O 2(g) CO 2(g) combustion (e) 2 Al 2 O 3(s) 4 Al (s) + 3 O 2(g) decomposition (f) 2 Hg (l) 2 HgO (s) synthesis (combustion) (g) 2 FeBr 3(s) 2 Fe (s) + 3 Br 2(g) decomposition 6. Reaction Type Reactants Synthesis element + element element + compound compound + compound Decomposition binary compound complex compound Combustion metal + oxygen nonmetal + oxygen fossil fuel 7. (a) 2 Na (s) + Cl 2(g) 2 NaCl (s) synthesis (b) 2 CuO (s) 2 Cu (s) decomposition (c) Cu (s) + Cl 2(aq) CuCl 2(s) synthesis 8. (a) 2 Li 2 O (s) 4 Li (s) 2 MgO (s) 2 Mg (s) ZnCl 2(s) Zn (s) + Cl 2(g) Mg(OH) 2(s) MgO (s) Copyright 2002 Nelson Thomson Learning Chapter 3 Chemical Reactions 55

2 S (s) SO 2(g) synthesis (combustion) 2 SO 2(g) 2 SO 3(g) synthesis (combustion) SO 3(g) synthesis (b) Sulfur trioxide is a byproduct of the combustion of gasoline in car engines. In the atmosphere it reacts with condensed water on dust particles, producing sulfuric acid. Atmospheric sulfuric acid is one of the acids that is responsible for the increased acidity of precipitation known as acid rain. 4. (a) Nitrogen monoxide decomposes into nitrogen and oxygen. Pt/Pd 2 N N 2(g) (b) The platinum/palladium catalytic converter built into today s automobiles catalyzes the decomposition of nitrogen monoxide which is a combustion engine exhaust pollutant into harmless nitrogen and oxygen. 3.3 SINGLE DISPLACEMENT REACTIONS (Page 128) 1. In single displacement reactions, like displaces like a metallic element takes the place of a metal in a compound; a nonmetallic element takes the place of a nonmetal in a compound. 2. An activity series is a list of elements arranged in order of their reactivity, based upon empirical evidence gathered from single displacement reactions. 3. (a) Zn (s) + CuCl 2(aq) Cu (s) + ZnCl 2(aq) (b) Br 2(aq) + CaCl 2(aq) NR (c) Pb (s) + 2 HCl (aq) + PbCl 2(aq) (d) Cl 2(aq) + 2 NaI (aq) 2 NaCl (aq) + I 2(s) (e) Ca (s) + Ca(OH (f) Au (s) + Zn NR (g) Sn (s) + 2 AgNO 3(aq) 2 Ag (s) + Sn(NO 3 (h) 2 Al (s) + 3 H 2 3 H 2(g) + Al 2 O 3(aq) (i) (j) Br 2(aq) + MgI 2(aq) MgBr 2(aq) + I 2(s) 2 Al (s) + 3 Zn 3 Zn (s) + Al 2 (SO 4 ) 3(aq) 4. Generally speaking, the more reactive elements will replace the less reactive elements. Thus, within the metal group, the more reactive metal elements are the ones with low electronegativity values and they will replace metal elements with higher electronegativity values. For example, lithium has an electronegativity value of 1.0 and will replace potassium, which has an electronegativity value of 0.8. (It should be noted that there are a number of exceptions to this generalization.) Within the nonmetal group, the more reactive nonmetal elements are the ones with high electronegativity values and they will replace nonmetal elements with lower electronegativity values. For example, fluorine has an electronegativity value of 4.0 and will replace chlorine, which has an electronegativity value of 3.0. (Again, it should be noted that there are a number of exceptions to this generalization.) 5. As you move from left to right within the same period, the elements of the periodic table show a general increase in electronegativity values. The most reactive metals are the ones with lower electronegativity values and are positioned at the left of a period. Thus, as you move from left to right within the same period, the metals become more electronegative and therefore less reactive. However, the most reactive nonmetals are the ones with high electronegativity values and are positioned at the right of a period. Thus, as you move from left to right within the same period, the nonmetals become more electronegative and therefore more reactive. Copyright 2002 Nelson Thomson Learning Chapter 3 Chemical Reactions 57

3 12. The student is to use the Internet to research the composition of various steels and to choose one alloy and list its properties and its applications. The student is then to write a short infomercial advertising the benefits of this material to potential users and to include any precautions necessary for its safe use. GO TO Chemistry 11, Teacher Centre 13. The student is to use the Internet to research the applications of aluminum and its alloys and the environmental issues surrounding aluminum production. The student is to use the findings to comment on the following statement: Risks to the environment posed by mining and refining aluminum are outweighed by the technological benefits of aluminum alloys. (Page 135) GO TO Chemistry 11, Teacher Centre Making Connections 14. The student is to research one of the careers listed on page 135 or a related career, and write a report that: (a) provides a general description of the nature of the work and how chemical reactions are involved; (b) describes the educational background and the length of study required to obtain employment in this field; (c) gives examples of programs offered by educational institutions leading to this career; (d) forecasts employment trends for this field; and (e) describes working conditions and salary. GO TO Chemistry 11, Teacher Centre 3.4 DOUBLE DISPLACEMENT REACTIONS (Page 138) 1. The following monatomic ions form compounds that have high solubility in water: Group 1 monatomic ions that form compounds with Cl,Br, and I. Group 1 and Group 2 monatomic ions that form compounds with S NH + 4 is the positive polyatomic ion that forms compounds that all have high solubility in water. 3. (a) KCl (aq) (i) Fe(OH) 3(s) (b) Ca(NO 3 (j) PbSO 4(s) (c) Na 2 (k) Ca 3 (PO 4 ) 2(s) (d) AgC 2 H 3 O 2(s) (l) KMnO 4(aq) (e) NH 4 Br (aq) (m) NH 4 NO 3(aq) (f) BaS (aq) (n) CoCl 2(aq) (g) PbI 2(s) (o) Ca (h) Ca(OH) 2(s) (Page 141) 4. The reaction involves two ionic compounds as reactants. 5. (a) Cu(NO 3 + MgCl 2(aq) CuCl 2(s) + Mg(NO 3 (b) 3 Ba(OH + Fe 2 (SO 4 ) 3(aq) 3 BaSO 4(s) + 2 Fe(OH) 3(s) (c) Mg(OH) 2(s) Mg (d) (NH 4 ) 2 S (aq) + Fe (NH 4 ) 2 + FeS (s) Copyright 2002 Nelson Thomson Learning Chapter 3 Chemical Reactions 59

4 6. AB + CD AD + CB As the equation above shows, the ions change partners to form products. This type of reaction commonly occurs in aqueous solutions. 7. (a) KNO 3(aq) (b) CaCl 2(aq) (c) Mg(OH) 2(s) (d) Al 2 (SO 4 ) 3(aq) (e) PbI 2(s) (f) Ca 3 (PO 4 ) 2(s) (g) (NH 4 ) 2 8. (a) 2 KCl (aq) + Cu(NO 3 ) 2 (aq) 2 KNO 3(aq) + CuCl 2(s) (b) MgCl 2(aq) + Ca(OH Mg(OH) 2(s) + CaCl 2(aq) (c) MgCl 2(aq) + Ca(OH CaCl 2(aq) + Mg(OH) 2(s) (d) 3 K AlCl 3(aq) 6 KCl (aq) + Al 2 (SO 4 ) 3(aq) (e) CuI 2(s) + PbSO 4(s) Cu + PbI 2(s) (f) 3 CaI 2(aq) + Pb 3 (PO 4 ) 2(s) 3 PbI 2(s) + Ca 3 (PO 4 ) 2(s) (g) (NH 4 ) 2 S (aq) + CaCO 3(s) CaS (aq) + (NH 4 ) 2 9. (a) single displacement (b) double displacement 10. (a) Cl 2(g) + 2 NaBr (aq) 2 NaCl (aq) + Br 2(g) single displacement (b) H NaOH (aq) 2 H 2 + Na 2 (c) 3 Ca(NO Na 3 PO 4(aq) Ca 3 (PO 4 ) 2(s) + 6 NaNO 3(aq) double displacement double displacement 11. (a) Al (s) + 3 AgNO 3(aq) 3 Ag (s) + Al(NO) 3(aq) single displacement (b) Cl 2(g) + 2 NaBr (aq) 2 NaCl (aq) + Br 2(g) (c) Zn (s) + Zn (d) 2 AgNO 3(aq) + MgCl 2(aq) 2 AgCl (s) + Mg(NO 3 (e) Na 2 C 2 O 4(aq) + CaCl 2(aq) CaC 2 O 4(aq) + 2 NaCl (aq) single displacement single displacement double displacement double displacement (f) 2 Na (s) + 2 NaOH (aq) single displacement (g) 3 KOH (aq) + FeCl 3(aq) 3 KCl (aq) + Fe(OH) 3(s) double displacement 12. (a) Ca 3 (PO 4 ) 2(s) calcium phosphate (b) 3 H 2 + Ca 3 (PO 4 ) 2(s) 2 H 3 PO 4(aq) + 3 CaSO 4(s) (c) The simple procedure of filtering could be employed to isolate aqueous phosphoric acid from the solid calcium phosphate. (d) If sodium phosphate is used in place of calcium phosphate as a reactant, the products of the reaction would be aqueous phosphoric acid and aqueous sodium sulfate. Sodium sulfate is highly soluble at SATP, and would pass through a simple filter. Thus the simple procedure of filtering would not be sufficient to isolate the phosphoric acid. The fertilizer manufacturer would prefer to avoid the additional costs that would be associated with a more involved process of isolating the phosphoric acid. 60 Unit 1 Matter and Chemical Bonding Copyright 2002 Nelson Thomson Learning

5 (d) Assign the following element identities: X = Li Y = Na Z = Mg 2 Li (s) + 2 LiOH (aq) 2 Li (s) + 2 HCl (aq) + 2 LiCl (aq) 2 Na (s) + 2 NaOH (aq) 2 Na (s) + 2 HCl (aq) + 2 NaCl (aq) Mg (s) + Mg(OH) 2(s) Mg (s) + 2 HCl (aq) + MgCl 2(aq) (e) All reactions are single displacement reactions. With respect to the reaction with water: Use a lighted splint to ignite the gas produced. A pop sound when ignited indicates hydrogen gas. The aqueous solution could be tested with ph paper to determine if it is basic. These tests would indicate that the reaction was a single displacement type, with the metal displacing hydrogen in the water (H 2 ) to produce hydrogen gas and a metal hydroxide. With respect to the reaction with acid: Use a lighted splint to ignite the gas produced. A pop sound when ignited indicates hydrogen gas. The aqueous solution could be evaporated and the remaining compound analyzed to determine if it is a metal chloride. These tests would indicate that the reaction was a single displacement type, with the metal displacing hydrogen in the acid (HCl (aq) ) to produce hydrogen gas and a metal chloride. Making Connections Pt 4. (a) 2K (s) + BeCl 2(s) Be (s) + 2 KCl (l) single displacement (b) Beryllium chloride should be stored dry within air and water vapour tight sealed containers. The substance should only be handled in environmentally enclosed and controlled areas, and all required protective equipment such as gas masks, protective clothing, and protective gloves should be worn. 5. (a) C (s) + SiO 2(l) Si (l) + CO 2(g) single displacement Si (s) + 2 Cl 2(g) SiCl 4(l) synthesis 2 Mg (s) + SiCl 4(l) Si (s) + 2 MgCl 2(aq) single displacement (b) Emissions of carbon dioxide gas (a product of the first reaction) cause rain to become slightly acidic. Carbon dioxide gas also contributes to the greenhouse effect, which may lead to global warming and dramatic climate changes. CHAPTER 3 REVIEW (Page 146) 1. The kinetic molecular theory states that all matter is made up of particles in continuous random motion. A gas has widely separated molecules in constant, chaotic motion. The average kinetic energy of the molecules is much larger than the energy associated with the attractive forces between them. With liquids, the attractive forces between molecules have energies comparable to the kinetic energies of the molecules. The attractive forces are able to hold the molecules close to each other. However, the attractive forces are not strong enough to hold the molecules rigidly in place. In fact, molecules within a liquid are able to move in a more or less chaotic fashion, allowing liquids to be poured, and to flow to take the shape of their container. With solids, the intermolecular attractions are sufficiently strong enough to hold the molecules rigidly in place. The average kinetic energy of the molecules is much smaller than the energy associated with the attractive forces between them. The particles of a solid are not free to move. However, the molecules within a solid may undergo vibrational motion. 64 Unit 1 Matter and Chemical Bonding Copyright 2002 Nelson Thomson Learning

6 2. The collision reaction theory suggests that particles must collide with the correct orientation and at sufficient speed to react. Chemical reactions will not occur when the collision orientation is not correct, and/or when the speed of collision is not sufficient. 3. (a) S O 2 8 SO 2 synthesis (combustion) (b) HBr + NaOH NaBr O (c) N H 2 2 NH 3 (d) PtCl 4 Pt + 2 Cl (e) 2 MgO + Si 2 Mg + SiO 2 double displacement synthesis decomposition single displacement (f) Na 2 S + 2 HCl 2 NaCl S double displacement (g) P O 2 P 4 O 10 (h) Zn + 2 HCl ZnCl 2 synthesis (combustion) single displacement 4. (a) potassium chlorate potassium chloride + oxygen 2 KClO 3(s) 2 KCl (s) + 3 O 2(g) (decomposition) (b) sodium + water (HOH) hydrogen + sodium hydroxide 2 Na (s) + 2 NaOH (single displacement) (c) carbon + oxygen carbon dioxide C (s) CO 2(g) (d) zinc + sulfuric acid zinc sulfate + hydrogen Zn (s) Zn (g) (combustion) (single displacement) (e) silver nitrate + potassium iodide silver iodide + potassium nitrate AgNO 3(aq) + KI (aq) AgI (s) + KNO 3(aq) (double displacement) (f) sodium sulfate + barium chloride barium sulfate + sodium chloride Na 2 + BaCl 2(aq) BaSO 4(s) + 2 NaCl (aq) (double displacement) (g) iron + oxygen iron(iii) oxide 4 Fe (s) + 3 O 2(g) 2 Fe 2 O 3(s) (combustion/synthesis) (h) sulfur trioxide + water sulfuric acid SO 3(g) (synthesis) 5. (c) calcium sulfate; (h) silver iodide; (i) copper(i) chloride; (j) lead(ii) sulfate are all of low solubility 6. Na 2 + Ca(NO 3 2 NaNO 3(aq) + CaSO 4(s) KI (aq) + AgNO 3(aq) KNO 3(aq) + AgI (s) NaCl (aq) + CuNO 3(aq) NaNO 3(aq) + CuCl (s) Na 2 + Pb(NO 3 2 NaNO 3(aq) + PbSO 4(s) 7. By referring to the relevant activity series. A metal will be displaced by a metal above it in the series; a nonmetal will be similarly displaced by a nonmetal. 8. (a) 2 Li (s) + 2 LiOH (aq) (b) 2 K (s) + 2 KOH (aq) (c) Cu (s) + 2 AgNO 3(aq) 2 Ag (s) + Cu(NO 3 (d) Fe (s) + NaCl (aq) NR (e) Mg (s) + Ca(NO 3 NR (f) 2 Al (s) + 6 HCl (aq) 3 H 2(g) + 2 AlCl 3(aq) (g) Pb (s) + Cu(NO 3 Cu (s) + Pb(NO 3 (h) F 2(g) + 2 HCl (aq) Cl 2(g) + 2 HF (aq) (i) I 2(s) + NaBr (aq) NR 9. (a) single displacement (b) solid iodine and potassium chloride Copyright 2002 Nelson Thomson Learning Chapter 3 Chemical Reactions 65

7 (c) Cl 2(g) + 2 KI (aq) I 2(s) + 2 KCl (aq) (d) Chlorine, being more electronegative, displaces the iodide ion. 10. (a) Assume their elemental states: fluorine, bromine, nitrogen. Nitrogen gas is unreactive; fluorine is more reactive than bromine as it has a higher electronegativity. (b) rubidium, potassium, magnesium. Rubidium is less electronegative than potassium, which is more reactive than magnesium. Applying Inquiry Skills 11. (a) 2 Li (s) + 2 LiOH (aq) Reasons: Group 1 metals are soft and silvery water is colourless the gas test indicates hydrogen the litmus test indicates one of the products is a base the flame test (bright red) indicates that lithium could be a constituent of one of the products (b) Reasonably sure. We don t know if the metal floated when it was put in the liquid (lithium would). If we assume the liquid was pure water, the metal in the reaction could be strontium (flame test). Sr (s) + Sr(OH To be sure that the metal wasn t strontium, another sample of the metal could be observed when it is put in water. If it floats (as lithium would), it can t be strontium (density 2.6 g/cm 3 ). A chemical test would involve adding sulfuric acid to the product solution. Strontium sulfate has low solubility, but lithium sulfate has high solubility. If sulfuric acid were added to the solution, and strontium ions were present, strontium sulfate should precipitate in a double displacement reaction: Sr(OH 2 H 2 + Sr It is also possible the liquid was water, but containing one or more solutes, for example, an acid. A test with ph paper or litmus paper would test for this kind of solute. 12. part 1: step 1, Ni(OH) 2(s) should form and be filtered step 2, adding the barium chloride should result in the precipitation of BaSO 4(s) Ni + 2 NaOH (aq) Na 2 + Ni(OH) 2(s) Na 2 + BaCl 2(aq) 2 NaCl (aq) + BaSO 4(s) both are double displacement reactions part 2: step 5, the mass of the crucible and contents should increase due to the synthesis of MgO (s) as the magnesium combusts 2 Mg + O 2 2 MgO (s) part 3: step 6, small bubbles may form on the zinc as the zinc slowly replaces hydrogen in water in a single displacement reaction; after the addition of sulfuric acid, gas should be generated more vigorously in another single displacement reaction. The small amount of zinc hydroxide produced in the first reaction should also react with the sulfuric acid in a double displacement reaction. step 7, the gas will pop, indicating hydrogen Zn (s) + Zn(OH) 2(s) Zn + Zn Zn(OH) 2(s) Zn 2 H 2(g) 2 H 2 Making Connections 13. Barium sulfate is a low-solubility solid. Because it does not dissolve, no barium ions are freed into solution within the patient and so there are no toxic effects. 14. Students are to investigate the refining process for a major industrial element, including any chemical reactions. GO TO Chemistry 11, Teacher Centre. 66 Unit 1 Matter and Chemical Bonding Copyright 2002 Nelson Thomson Learning

8 5.2 BALANCING CHEMICAL EQUATIONS (Page 211) 1. Conservation of mass requires that a reaction equation somehow represent the fact that total reactant mass equals total product mass. 2. (a) Mg (s) + 2 HCl (aq) MgCl 2(aq) (g) (b) (c) 2 Na (s) 2 NaOH (aq) (g) CaCO 3(s) + 2 HCl (aq) CaCl 2(s) + CO 2(g) (d) Cu (s) + 4 HNO 3(aq) Cu(NO N (e) 2 C 3 H 6(g) + 9 O 2(g) 6 CO 2(g) + 6 H 2 3. (a) 2 H 2(g) 2 H 2 (b) Correct (c) Pb (s) + 2 AgNO 3(aq) 2 Ag (s) + Pb(NO 3 (d) Correct 4. Fe(NO 3 ) 3(aq) 1 3 LiOH (aq) 3 LiNO 3(aq) 1 Fe(OH) 3(s) (Page 213) 5. The formula coefficients of a chemical equation represent the mole ratio of substances in the reaction. 6. Consider: C (s) CO 2(g) This reaction equation shows clearly that the number of moles of substances in reactions is not conserved: two moles of reactants become one mole of product NO 2(g) H 2 2 HNO 3(aq) N The mole ratio is 3:1:2:1 for the reaction equation as written here. 8. In a chemical industry, the amounts produced and consumed in reactions determine the economics of the process so the mole ratio is essential knowledge for determining whether any process is practical. (Page 214) 9. Fertilizers increase crop production. Without them there would not be enough food produced to support the current population of the Earth. 10. Fertilizer excess that enters the environment can cause serious changes in watersheds, affecting all living things that depend on that water supply. Making Connections 11. Typical reports might select groups like Ducks Unlimited, Canada, which is dedicated to actively working to preserve Canada s wetlands. DU emphasize that not only do wetlands provide habitat for a complex ecosystem of living things; they act as natural filters for our water supply. GO TO Chemistry 11, Teacher Centre. 116 Unit 2 Quantities in Chemical Reactions Copyright 2002 Nelson Thomson Learning

9 Explore an Issue Role Play: Controlling the Use of Fertilizers (Page 215) GO TO Chemistry 11, Teacher Centre. SECTION 5.2 QUESTIONS (Page 215) 1. Balancing by inspection uses a trial-and-error approach to determining the coefficients of a reaction equation. 2. (a) 2 Al (s) + 3 CuCl 2(aq) 3 Cu (s) + 2 AlCl 3(aq) (b) Cu (s) + 2 HCl (aq) + CuCl 2(aq) (c) 2 HgO (s) 2 Hg (l) (d) CH 4(g) C + 3 H 2(g) (step i) C (g) CH 3 OH (g) (step ii) 3. (a) C (s) CO 2(g) (b) S 8(s) + 8 O 2(g) 8 SO 2(g) (c) Cu(OH) 2(s) 2 H 2 + Cu (d) CaSiO 3(s) SO 3(aq) SiO 3(aq) + CaSO 3(s) (e) CaCO 3(s) + 2 HNO 3 + Ca(NO 3 (f) 2 Al (s) + 3 H 2 3 H 2(g) + Al 2 (SO 4 ) 3(aq) (g) SO 2(g) SO 3(aq) (h) 2 Fe (s) + 3 H 2 SO 3(aq) 3 H 2(g) + Fe 2 (SO 3 ) 3(s) (i) (j) N 2(g) 2 N CO 2(g) (k) CH 4(g) + 2 O 2(g) CO 2(g) (l) 2 C 4 H 10(g) + 13 O 2(g) 8 CO 2(g) + 10 H 2 (m) 2 FeS (s) + 3 O 2(g) 2 FeO (s) + 2 SO 2(g) (n) 2 H 2 S (g) + 3 O 2(g) 2 H SO 2(g) (o) 2 CaCO 3(s) + 2 SO 2(g) 2 CaSO 4(s) + 2 CO 2(g) 4. (a) 4 CH 3 NO 2(l) + 7 O 2(g) 4 CO 2(g) + 6 H NO 2(g) The mole ratio is 4:7:4:6:4 for the reaction equation as written here. (b) 2 Al (s) + 3 CuCl 2(aq) 3 Cu (s) + 2 AlCl 3(aq) The mole ratio is 2:3:3:2 for the reaction equation as written here. Making Connections 5. Fertilizers are sold with information about what area can be treated per kilogram. Farmers would have to do area calculations, cost calculations, and predictive calculations about the value of projected increased crop yield. Copyright 2002 Nelson Thomson Learning Chapter 5 Quantities in Chemical Equations 117

10 CHAPTER 5 REVIEW (Page 252) 1. (a) In a reagent mix, the one consumed first, causing the reaction to cease, is the limiting reagent. Some of the other reagent will remain, so it is said to be in excess. (b) A chemical reaction involves change in the electrons of an entity; a nuclear reaction involves change in the atomic nuclei. (c) Alpha decay involves the emission of an alpha particle (helium-4 nucleus) from an atomic nucleus, while beta decay involves the emission of a beta particle (electron) from a nucleus. (d) The quantity of product predicted by stoichiometric calculation is the theoretical yield. When the reaction is carried out, the measured quantity of product obtained is the actual yield. (e) An empirical formula shows the simplest integral ratio of component entities. A molecular formula shows the actual numerical ratio of atoms in a molecule of the substance. 2. (a) 2 SO 2(g) O 2(g) 2 SO 3(g) (b) SO 3(g) H 2 (c) CaO (s) SO 2(g) O 2(g) CaSO 4(s) (d) CaO (s) H 2 SO 3(aq) CaSO 3(s) (e) Al 2 (SiO 3 ) 3(s) 3 H 2 3 H 2 SiO 3(aq) Al 2 (SO 4 ) 3(s) 3. (a) Th -1 0 e Pa (b) Pa -1 0 e U I -1 0 e Xe 5. (a) I Xe e (b) 59 26Fe Co e (c) Rn Po He (d) Cf B Lr n (e) Pu + 4 2He Cm n 6. The mass number drops by 28, which means 28/4 = 7 alpha decays. The atomic number only drops by 10, which means = 4 beta decays. Re Os e Li 8 3 Li n Bi Au He Tm Yb e In Sn e 8. 2 C 8 H 18(l) 25 O 2(g) 16 CO 2(g) 18 H g m g/mol g/mol 1 mol n C8 H = 692 g g n C8 H = 6.06 mol 18 n CO2 = 6.06 mol Unit 2 Quantities in Chemical Reactions Copyright 2002 Nelson Thomson Learning

11 (f) From the solubility curve drawn in (e), the solubility of Ca(OH) 2(s) at 22 C is 0.17 g/100 ml, or 0.17 g/0.100 L. v Ca(OH)2 1.0 L c Ca(OH) g/100 ml 0.17 g/0.100 L 0.17 m Ca(OH)2 1.0 L 0.10 g 0 L m Ca(OH)2 1.7 g The minimum mass of calcium hydroxide required to make up 1 L of saturated solution will be about 1.7 g. The actual mass one would use should be much more than this say, 15 to 20 g, to ensure a large excess of solute, which in turn ensures saturation. Note: In this particular instance the volume of the solute added is very small compared to the volume of the solvent; so the difference between solvent volume and solution volume may be considered negligible. (g) The solubility of calcium hydroxide is anomalous unlike most solids it decreases in solubility with increasing temperature. The generalization we use is still valid and useful for most soluble solids. It just needs to be understood that generalizations are exactly that statements that generally (not invariably) describe events correctly. Applying Inquiry Skills 9. Prediction (a) The solubility of potassium chlorate should increase with an increase in temperature, according to the generalization for the solubility of solids, and also according to Figure 2 on page 316 of the text. Analysis (b) 60 Solubility Curve for Potassium Chlorate 50 Solubility (g/100 ml) Temperature ( C) (c) According to the Evidence, the solubility of potassium chlorate increases with increasing temperature, for solution temperatures from 0 C to 100 C. Making Connections 10. Gases such as oxygen are less soluble in warm water, so active fish that require high oxygen levels may not thrive in water that is warmed by an outside source, such as a power plant. In addition, power plants may alter the ecology of a body of water by preventing it from freezing over in the winter. This would attract waterfowl that would feed on aquatic organisms normally under the ice at this time. (Page 325) 11. (a) The high/low solubility cutoff point is 0.10 mol/l at SATP. (b) The 0.10 mol/l cutoff is useful because most laboratory solutions are within an order of magnitude of this concentration, and because most ionic solids are either markedly more or less soluble than this value. (c) The table need only be used to determine the solubility of an ionic solid if the solid does not contain a group I ion, an ammonium ion, or a nitrate ion because such compounds are always highly soluble. To determine the solubility of any other ionic solid, find the anion in its column heading, and look down the column to find the row Copyright 2002 Nelson Thomson Learning Chapter 7 Solubility and Reactions 199

12 Experimental Design Hard water is run through a pipe to a tap, and samples are tested for hardness, with and without a magnet being attached to the pipe. (b) Evaluation The original design is obviously useless in light of the new understanding of the claim made for the magnet; it is not testing the claimed result. New Experimental Design Hard water is run through identical piping that has and has not magnets attached. After several months, the piping is cut and the ease of removing the scaling from the inside of the pipe is determined. Making Connections 7. high sodium ion concentration WATER SOFTENING cleaner laundry; no scale formation REGENERATION high sodium ion concentration high calcium ion and saltwater discharge to the environment 7.3 REACTIONS IN SOLUTION (Page 332) 1. (a) silver sulfide: low solubility (b) magnesium nitrate: high solubility (c) zinc carbonate: low solubility 2. (a) Precipitate forms: SrSO 4(s) (b) No precipitate forms (c) Precipitate forms: CuSO 3(s) (Page 335) 3. Sr(NO 3 Na 2 SrCO 3(s) 2 NaNO 3(aq) Sr(aq) 2+ 2 NO 3(aq) 2Na+ (aq) CO2 3(aq) SrCO 3(s) 2 Na (aq) + 2 NO 3(aq) Sr(aq) 2+ CO2 3(aq) SrCO 3(s) 4. (a) Compounds could be any four of: copper(ii) nitrate, copper(ii) sulfate, copper(ii) acetate, copper(ii) chloride, copper(ii) bromide, or copper(ii) iodide. Choose copper(ii) nitrate as the example: (b) 2 Al (s) 3 Cu(NO 3 3 Cu (s) 2 Al(NO 3 ) 3(aq) (c) 2 Al (s) 3 Cu(aq) 2+ 6 NO 3(aq) 3 Cu (s) 2 Al(aq) 3+ 6 NO 3(aq) (d) 2 Al (s) 3 Cu(aq) 2+ 3 Cu (s) 2 Al(aq) Cl 2(g) 2 Br (aq) Br 2(l) 2 Cl (aq) Copyright 2002 Nelson Thomson Learning Chapter 7 Solubility and Reactions 203

13 6. Ca(aq) 2+ OOCCOO2 (aq) CaOOCCOO (s) or (if the oxalate ion formula is written in condensed form) Ca(aq) 2+ C 2 O2 4(aq) CaC 2 O 4(s) 7. Pb (s) 2 Ag (aq) + Pb(aq) 2+ 2 Ag (s) Making Connections 8. (a) Fe 3+ (aq) 3 OH (aq) Fe(OH) 3(s) (b) Filtration to remove the precipitate is the most likely process. Explore an Issue Debate: Producing Photographs (Page 336) (a) At first glance, it seems that digital cameras are more environmentally friendly than film cameras: they don t require film, film canisters, developing paper, or processing chemicals. However, this conclusion is based upon the assumption that only the final products affect the environment. (b) To argue against the proposition you need to recognize that the whole story of a product must be considered, including everything from the extracting of resources to manufacturing through disposal. For example, are there components of the digital camera that during manufacture cause the emission of toxins into the environment, or, when the camera must be disposed of, are there environmental concerns? (c) Recognize that the resolution requires an environmental perspective only; you need not consider, for example, economic, social, and technological arguments. In your investigation, you could look at subtopics such as raw materials, manufacturing, the developing process, the developing technology (and its environmental impact back to its origins), and disposal. (d) Consider the logic of the presentation and the quantity of evidence used to support the position taken. Were all stages from pre-manufacturing through post-disposal considered? SECTION 7.3 QUESTIONS (Page 336) 1. Pb(aq) 2+ SiO2 3(aq) PbSiO 3(s) 2. 3 Ca(aq) 2+ 2 PO3 4(aq) Ca 3 (PO 4 ) 2(s) 3. Cu (s) 2 Ag (aq) + Cu(aq) 2+ 2 Ag (s) Making Connections 4. Student answers will vary widely, as they will be specific to the regulations controlling local hazardous waste facilities. GO TO Chemistry 11, Teacher Centre. 7.4 WASTE WATER TREATMENT (Page 340) 1. Problems from the release of untreated sewage include: transmission of disease, lowering of oxygen levels, and rapid growth of aquatic plant life. 2. A high BOD reading is an indication that bacteria are using up oxygen to decompose organic material in the water. This is a problem for any oxygen-using life form in the water. 204 Unit 3 Solutions and Solubility Copyright 2002 Nelson Thomson Learning

14 (Page 346) happen to produce coloured flames. Other possible cations, not to mention the anions in each of these solutions, cannot be identified this way. As well, solution E may contain either or both of two cations, since they both produce the same result. 5. Qualitative analysis determines what is in a sample, and quantitative analysis determines how much is present. 6. A diagnostic test statement always includes procedure, evidence, and analysis steps. For example: If a gas is bubbled through limewater, and a white precipitate forms, then the gas is likely to contain carbon dioxide. 7. Precipitates could be formed with the listed ions by adding: (a) OH, CO 2 3, PO 3 4, or SO 2 3 aqueous ions. (b) SO 2 4, CO 2 3, PO 3 4, or SO 2 3 aqueous ions. (c) Ag +, Pb 2+, Tl +, Hg 2+ 2, or Cu + aqueous ions. (d) Ag +, Pb 2+, Ca 2+, Ba 2+, Sr 2+, or Ra 2+ aqueous ions. Applying Inquiry Skills 8. (a) To precipitate carbonate ions from a sample, without at the same time precipitating sulfide ions, add a compound that supplies any Group II cation, and an anion that is always soluble in combination (e.g., calcium nitrate, barium nitrate, or magnesium nitrate). (b) One example: Ca 2+ (aq) CO2 3(aq) CaCO 3(s) 9. Experimental Design Calcium nitrate solution is added to the test solution sample. If a precipitate forms it is filtered, and silver nitrate solution is added to the filtrate (or to the original sample, if no precipitate formed in the initial test). Making Connections 10. There are innumerable examples of qualitative analysis in society. Common examples include environmental tests for lead (or other heavy metals) in water supply systems; continuous monitoring by household detectors (carbon monoxide or natural gas in houses, propane in trailers); simple swimming pool or aquarium water-testing kits (including quantitative analysis); or even home pregnancy tests. There are also hundreds of industrial and commercial examples of qualitative analysis. There are many career opportunities as an analyst. GO TO Chemistry 11, Teacher Centre. SECTION 7.5 QUESTIONS (Page 346) 1. The precipitation reactions are: (a) Pb(aq) 2+ 2 Cl (aq) PbCl 2(s) (b) Zn(aq) 2+ S 2 (aq) (d) Ag + (aq) (e) 3 Ba 2+ (aq) + 2 PO3-4(aq) ZnS (s) C 2 H 3 O 2(aq) AgC 2 H 3 O 2(s) Ba 3 (PO 4 ) 2(s) (f) Ca 2+ (aq) 2 OH (aq) Ca(OH) 2(s) 2. (a) yellow-brown (b) colourless (c) blue (d) green (e) colourless 3. (a) Calcium (yellow-red flame test) can be distinguished from the other ions by a flame test, but lithium and strontium both give bright red flame tests, and so cannot be distinguished from each other in this way. Copyright 2002 Nelson Thomson Learning Chapter 7 Solubility and Reactions 207

15 (b) Adding sulfate (or carbonate, phosphate, or sulfite) ions to the two unidentified test solutions (aqueous sodium sulfate, for instance) would precipitate the strontium ions, but not the lithium ions. Applying Inquiry Skills 4. (a) Experimental Design The solution is flame tested. (b) Evaluation The experimental design is seriously flawed, because both ions produce coloured flames. If the initial flame test is bright red, there is no way to know whether potassium ions are present, because the violet colour will be hidden by the strontium ion colour. Alternative answer: (a) Experimental Design Sodium sulfate is added to the solution. Any precipitate is filtered and then the filtrate or original solution is flame tested. (b) Evaluation The experimental design is not valid. Although you will know with certainty whether strontium ions are present or not, based upon whether a precipitate forms or not, you will not be able to determine whether potassium ions are present, due to the masking of the potassium flame colour by the sodium flame colour. If cobalt-blue glass is employed in the materials and the procedure, then the design would be valid. (The cobalt-blue glass filters the yellow sodium colour from the flame and allows one to determine whether potassium is present or not.) Alternately, the cation for the sodium solution must be chosen to have a colourless flame test, e.g., hydrogen. (Unfortunately, a list of colourless flame-test ions is not provided in the text and would have to be researched.) 5. Experimental Design Sodium chloride solution is added to the sample. If a precipitate forms, it is filtered. Sodium hydroxide solution is added to the filtrate (or sample, if no precipitate forms). If a precipitate forms, it is filtered. Sodium carbonate (or sulfate) solution is added to the filtrate (or sample, if no precipitate forms). Note: A precipitate in the initial step (when you use any soluble halide ion compound) indicates that thallium ions are present. A precipitate in the second step (when you use any soluble hydroxide compound) indicates that calcium ions are present. A precipitate in the third step (when you use any soluble sulfate, carbonate, phosphate, or sulfite compound) indicates that barium ions are present. The sequence of steps is very important: sodium carbonate cannot be added first, for example. 6. (a) The Experimental Design is satisfactory. The solution colour test can confirm the presence of copper(ii) ions, but not calcium ions; and any red in the flame test will confirm the presence of calcium ions. (b) Alternative Experimental Design Sodium sulfate solution is added to the sample solution. If a precipitate forms, it is filtered. Sodium carbonate solution is added to the filtrate (or sample, if no precipitate forms). Note: A precipitate in the initial step (when you use any soluble sulfate compound) indicates that calcium ions are present. A precipitate in the second step (when you use any soluble sulfide, carbonate, phosphate, or sulfite compound) indicates that copper(ii) ions are present. 7. Any carbonated beverage is a home solution with a gaseous solute. A diagnostic test is: If a gas is bubbled through limewater, and a white precipitate forms, then the gas contains carbon dioxide. Another example would be household ammonia, or any of several spray window cleaners containing ammonia. The diagnostic test would be the characteristic odour of ammonia. 8. Sodium carbonate is a typical home solution with a solid solute; e.g., as a water softener (washing soda) in laundry detergents. Diagnostic tests for this example would be flame testing for sodium ions, and precipitation using calcium chloride solution, for carbonate ions. 9. Experimental Design Oxalic acid is added to sample solutions of nitrate or chloride compounds of as many metal cations as can be found in the school laboratory supplies. Any precipitate formation is recorded. 10. Experimental Design A solution of the product is first flame tested; then a solution of calcium chloride is added. Note: A yellow flame test indicates sodium; a precipitate indicates carbonate ions. 208 Unit 3 Solutions and Solubility Copyright 2002 Nelson Thomson Learning

16 CHAPTER 7 SUMMARY (Page 357) Make a Summary solid gas industrial chemical production immiscible miscible temperature effects industrial softening high solubility categories water hardness consumer softening materials low solubility crystallization design solubility reactions waste water treatment industrial/ municipal consumer (septic tank) primary procedure net ionic equations flame colour solution colour skills quantitative analysis design skills precipitation reactions materials procedure quantitative analysis excess and limiting reagents tertiary solution stoichiometry yield and % yield secondary materials filtration skills procedure Reflect on your Learning 1. I now know that most liquids (even water) in my home or laboratory are solutions rather than pure substances. The liquid can be tested using some combination of the following methods: with litmus or ph paper; for electrical conductivity; with a flame test; by crystallization; by precipitation; by heating; by odour; by colour; and/or by feel (not recommended). 2. From my experience I now know that it is possible to increase the rate of dissolving by, for example, stirring the solution in contact with excess solute. But no matter how much you stir, there comes a point at which you cannot get any more solute to dissolve in the solvent; the solution is saturated. 3. Evidence for a chemical reaction includes a change in state (forming a precipitate or a gas), a change in temperature, and a change in colour. Further observation would indicate that the change does not reverse spontaneously. Qualitative analysis would indicate that one or more new chemicals are produced by the change. Copyright 2002 Nelson Thomson Learning Chapter 7 Solubility and Reactions 213

17 CHAPTER 7 REVIEW (Page 358) 1. Combinations (a), (b), (c), (d), and (f) will react, but only (a), (c), (d), and (f) will form precipitates. The reaction equations are: (a) Cu(aq) OH (aq) Cu(OH) 2(s) (b) H (aq) + + H (aq) (c) 3 Ca(aq) PO3 4(aq) Ca 3 (PO 4 ) 2(s) (d) Ag (aq) + + Cl (aq) AgCl (s) (f) Cu (aq) + Cl (aq) CuCl (s) 2. (a) Zn(aq) 2+ + CO2 3(aq) ZnCO 3(s) (b) Pb(aq) 2+ + CO2 3(aq) PbCO 3(s) (c) 2 Fe(aq) CO2 3(aq) Fe 2 (CO 3 ) 3(s) (d) Cu(aq) 2+ + CO2 3(aq) CuCO 3(s) (e) Ag (aq) + + CO2 3(aq) Ag 2 CO 3(s) (f) Ni(aq) 2+ + CO2 3(aq) NiCO 3(s) (g) The choice of sodium carbonate is good because carbonate ions form low soluble compounds with most metallic ions and the compound is soluble, common, and inexpensive. 3. (a) Al(aq) OH (aq) Al(OH) 3(s) and Ca(aq) 2+ + SO2 4(aq) CaSO 4(s) or 2 Al(aq) SO2 4(aq) + 3 Ca2+ (aq) + 6 OH (aq) 2 Al(OH) 3(s) + 3 CaSO 4(s) Note: The effective precipitate for clarifying the water is the flocculent precipitate, Al(OH) 3(s). (b) 3 Ca(aq) PO3 4(aq) Ca 3 (PO 4 ) 2(s) (c) Mg(aq) OH (aq) Mg(OH) 2(s) (d) Fe(aq) OH (aq) Fe(OH) 3(s) 4. Cu(aq) Ions of alkali metals, as well as hydrogen, ammonium, and nitrate ions, form compounds with high solubility. 6. A violet flame indicates potassium ions. A precipitate with Hg (aq) + could indicate any anion on the solubility chart except sulfate, nitrate, or acetate. The compound in solution might be KCl, KBr, K 2 S, K 2 SO 4, KOH, K 3 PO 4, or In aqueous solution: (a) Cu + is green, Cu 2+ is blue. (b) Fe 2+ is pale green, Fe 3+ is yellow-brown. (c) CrO 2 4 is yellow, Cr 2 O 2 7 is orange. 8. Ca(aq) 2+ and Mg2+ (aq) 9. (a) Na 2 Cu Na 2 CuCO 3(s) v 4.54 L 1.25 mol/l mol/l n CuSO L mol mol 1 L 214 Unit 3 Solutions and Solubility Copyright 2002 Nelson Thomson Learning

18 Applying Inquiry Skills 12. Baking soda will react both with strong bases and with acids. It releases carbon dioxide gas upon reaction with acids. Since it can react either as an acid or as a base, it is not simple to predict how it will react in any given situation. GO TO Chemistry 11, Teacher Centre. Making Connections 13. Uses of baking soda include: baking reacts with food acids to produce CO 2(g) for leavening brushing teeth a mild non-abrasive non-toxic cleaner acid spills neutralizes them for cleanup base spills neutralizes them for cleanup odour removal reacts with acidic or basic odorous gases in refrigerators, kitchens, and carpets firefighting releases carbon dioxide, which smothers flames cleaning makes a solution for washing surfaces 8.5 ACID BASE REACTIONS (Page 394) 1. Acids react with active metals to produce hydrogen and an ionic compound; react with carbonate compounds to produce carbon dioxide gas and water; and neutralize bases to produce water. 2. (a) 2 HBr (aq) Zn (s) ZnBr 2(aq) HBr (aq) NaOH (s) NaBr (aq) 2 HBr (aq) Na 2 CO 3(s) 2 NaBr (aq) or 2 HBr (aq) Na 2 CO 3(s) CO 2(g) 2 NaBr (aq) (b) The first neutralization produces hydrogen, which is flammable and dangerous, and uses zinc, which is not commonly available. The second neutralization uses lye (a strong base), which is very corrosive and not easy to handle. The third neutralization is practical. It uses washing soda, which is non-hazardous, inexpensive, and commonly available; and produces no dangerous products. 3. (a) 3 H 2 C 2 O 4(aq) 2 Al (s) 3 H 2(g) Al 2 (C 2 O 4 ) 3(s) (b) H 2 C 2 O 4(aq) CaCl 2(aq) 2 HCl (aq) CaC 2 O 4(s) or H 2 C 2 O 4(aq) Ca 2+ (aq) 2 H+ (aq) CaC 2 O 4(s) (c) 3 H 2 C 2 O 4(aq) FeCl 3(aq) 6 HCl (aq) Fe 2 (C 2 O 4 ) 3(s) or 3 H 2 C 2 O 4(aq) Fe 3+ (aq) 6 H+ (aq) Fe 2 (C 2 O 4 ) 3(s) Iron(III) ions are removed from solution by reaction with oxalate, effectively preventing the body from using them. Practice (Page 399) 4. Acids react with active metals to produce hydrogen and an ionic compound; react with carbonate compounds to produce carbon dioxide gas and water; and neutralize bases to produce water. 5. The requirements are that the chemical reaction must be spontaneous, rapid, quantitative, and stoichiometric. 6. The two reactants in a titration are the sample, usually in an Erlenmeyer flask, and the titrant, usually in a buret. 7. A standard solution is one with a precisely known concentration. 230 Unit 3 Solutions and Solubility Copyright 2002 Nelson Thomson Learning

19 SECTION 8.5 QUESTIONS (Page 401) 1. Answers will vary, but may include the following typical acid reactions. Reaction with active metals: 2 HCl (aq) Mg (s) MgCl 2(aq) Reaction with strong bases: HNO 3(aq) NaOH (s) NaNO 3(aq) Reaction with carbonate compounds: 2 HCl (aq) K 2 CO 3(s) 2 KCl (aq) or 2 HCl (aq) K 2 CO 3(s) CO 2(g) 2 KCl (aq) 2. Al(OH) 3(s) 3 HCl (aq) AlCl 3(aq) 3 H g v g/mol 0.10 mol/l 1 mol n Al(OH) g mol g n HCl mol mol 1 v HCl 1 L mol mol v HCl 0.35 L or v HCl 1 ol m Al( g Al(OH) g A H O ) 3 H l(o ) m l o H l C 1 L HC 1m 3 l o Al H (O ) m ol l H Cl v HCl 0.35 L The volume of hydrochloric acid neutralized is 0.35L. 3. Ca(OH) 2(s) H 2 CaSO 4(s) 2 H g v g/mol mol/l n Ca(OH) mol g mol g n H2 SO mol mol v H2 SO L mol mol v H2 SO L 4 or v H2 SO m ol C a( OH 1 m ol H g Ca(OH) g Ca( OH )) 2 2SO 4 1 m ol Ca( H O ) L H 2 SO 4 v H2 SO L The volume of lake water sulfuric acid that can be neutralized is L (or m 3 ). Copyright 2002 Nelson Thomson Learning Chapter 8 Acids and Bases 233

20 CHAPTER 8 REVIEW (Page 403) 1. (a) An acid is a substance that dissolves to form a conducting solution that turns blue litmus red, neutralizes bases, reacts with active metals to form hydrogen gas, and reacts with carbonate compounds to form carbon dioxide gas. (b) A base is a substance that dissolves to form a conducting solution that turns red litmus blue, and neutralizes acids. 2 (a) sodium hydroxide base (b) acetic acid acid (c) magnesium hydroxide base (d) hydrochloric acid acid (e) calcium hydroxide base (f) (aqueous) ammonia base\ 3 (a) basic: NaOH (s) Na (aq) + OH (aq) (b) acidic: HC 2 H 3 O 2(aq) H + (aq) C 2 H 3 O 2(aq) (c) basic: Mg(OH) 2(s) Mg 2+ (aq) 2 OH (aq) (d) acidic: HCl (aq) H (aq) + Cl (aq) (e) basic: Ca(OH) 2(s) Ca(aq) 2+ (aq) (f) basic: NH 3(aq) H 2 NH + 4(aq) OH (aq) 4. (a) [H(aq) + ] is much greater in the hydrochloric acid solution. (b) In hydrochloric acid, essentially all of the HCl molecules are dissociated into ions. In acetic acid, only a very small percentage of HC 2 H 3 O 2 molecules are dissociated. (c) The same volume of NaOH (aq) would be required for each neutralization reaction. 5. In order of increasing ph, the solutions are: HCl (aq),hc 2 H 3 O 2(aq), NaCl (aq),nh 3(aq), NaOH (aq) 6. (a) ph log [H(aq) + ] log [ mol/l] ph 2.12 (b) ph log [H(aq) + ] log [ mol/l] ph (a) [H(aq) + ] 10 ph mol/l [H(aq) + ] mol/l (b) [H(aq) + ] 10 ph mol/l [H(aq) + ] mol/l 8. Electrical conductivity, ph, and rate of reaction with active metals can all be used to rank acids in terms of strength. 9. (a) HNO 2(aq) has a higher ph (is less acidic, more basic). <50% (b) HNO 2(aq) H 2 H 3 O (aq) + NO 2(aq) >99% Copyright 2002 Nelson Thomson Learning Chapter 8 Acids and Bases 237

21 HNO 3(aq) H 2 H 3 O (aq) + NO 3(aq) As shown, nitric acid transfers protons to water completely, whereas in nitrous acid the transfer is much less than 50%, making the solution much less acidic. 10. [H + (aq)] is ten times as concentrated in ph 5 as in ph Concept Main Idea Limitations oxygen acids contain oxygen and doesn t explain solutions of HCl (g), or why some oxides make react with limestone basic solutions hydrogen acids contain hydrogen and doesn t explain acidic solutions of SO 2(g), or basic solutions from react with active metals to produce hydrogen gas compounds containing hydrogen, e.g., NH 3(g) Arrhenius acids dissolve in water to doesn t explain nonaqueous solutions, or hydrogen produce H+ (aq) containing substances that can neutralize both acids and bases 12. acid base conjugate acid conjugate base (a) HSO 4(aq) HCO 3(aq) H 2 SO 2 4(aq) (b) HSO 4(aq) HPO 2 4(aq) H 2 PO 3(aq) SO 2 4(aq) (c) H 2 PO 4(aq) H 2 BO 3(aq) H 3 BO 3(aq) HPO 2 4(aq) (d) HCO 3(aq) HS (aq) H 2 S (aq) CO 2 3(aq) (e) HSO 3(aq) NH 3(aq) NH 4(aq) + SO 2 3(aq) 13. (a) NH 3(aq) ammonia B-L acid or base (b) NH 4(aq) + ammonium ion B-L acid (c) NO 2(aq) nitrite ion B-L base (d) NO 3(aq) nitrate ion B-L base 14. (a) conjugate acid base pairs are: PO 3 4(aq) and HPO2 4(aq) and: H 2 O (aq) and OH (aq) (b) PO 3 4(aq) is a strong base that can only react as a base with water, so it must form a basic solution. 15. (a) H 2 SO 3(aq) + OH (aq) HSO 3(aq) (b) HSO 3(aq) + OH (aq) SO2 3(aq) 16. (a) NaH + HCl (aq) + NaCl (aq) HCO 3(aq) + H 3 O+ (aq) (b) NaH + NaOH (aq) Na 2 HCO 3(aq) + OH (aq) CO2 3(aq) (c) HCO 3(aq) + H 3 O+ (aq) B A A B HCO 3(aq) + OH (aq) CO2 3(aq) A B B A The conjugate acid base pairs are: H 3 O (aq) + and H 2 and H 2 and HCO 3(aq) H 2 and OH (aq) and HCO 3(aq) and CO2 3(aq) (d) The hydrogen carbonate ion may act as either an acid or as a base; it is amphiprotic. 17. A chemical reaction suitable for titration must be spontaneous, fast, stoichiometric, and quantitative. 18. You must know the concentration of one reactant solution accurately to calculate precise results. 238 Unit 3 Solutions and Solubility Copyright 2002 Nelson Thomson Learning

22 19. (a) titration: a laboratory procedure involving the carefully measured and controlled addition of a standard solution from a buret into a measured volume of a sample solution (or the sample solution could be in the buret...) (b) titrant: the solution in the buret during a titration (c) endpoint: the point in a titration at which a sharp change in a property occurs (e.g., a colour change) 20. The acid reacts with an active metal to produce hydrogen gas. H 2 + Zn (s) Zn (g) The acid is partially neutralized by a basic solution. H 2 + Na 2 Na 2 The acid is completely neutralized by a strong basic solution. H 2 + Zn (s) Zn (g) Applying Inquiry Skills 21. The equipment required for the precision given would be: (a) a volumetric flask (b) a 10-mL graduated cylinder or a 10-mL graduated pipet (c) a 10-mL volumetric pipet 22. Experimental Design The ph is measured for samples of an acid and of a base. The samples are diluted tenfold, and the ph measured again. Materials HCl (aq) NaOH (aq) two 150-mL beakers 100-mL graduated cylinder ph meter 23. (a) Analysis Solution 1 is NaH, because it is basic, but not with the highest ph, and conducts well. Solution 2 is KNO 3(aq), because it is neutral, and conducts well. Solution 3 is H 2 SO 3(aq), because it is acidic, but not with the lowest ph, and conducts poorly. Solution 4 is HCl (aq), because it is acidic, with the lowest ph, and conducts well. Solution 5 is NaOH (aq), because it is basic, with the highest ph, and conducts well. (b) Evaluation The experimental design is judged adequate because the experiment produces evidence needed to answer the question with a high degree of certainty. 24. (a) Evidence Table 2: Titration of ml of mol/l Na 2 with HCl (aq) Trial Final buret reading (ml) Initial buret reading (ml) Volume of HCl (aq) added Colour at endpoint red orange orange orange (b) Analysis Na 2 2 HCl (aq) 2 NaCl (aq) ml 17.1 ml mol/l C n Na2 CO ml mol 1.20 mmol 3 1 L n HCl 1.20 mmol mmol 1 Copyright 2002 Nelson Thomson Learning Chapter 8 Acids and Bases 239