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Министерство образования и науки Российской Федерации Федеральное агентство по образованию Южно-Уральский государственный университет Кафедра аналитической химии Ш143.21-9 Д182 Е.И. Данилина ХИМИЯ НА АНГЛИЙСКОМ ЯЗЫКЕ Модуль 1 БАЗОВЫЕ ХИМИЧЕСКИЕ ПОНЯТИЯ Учебное пособие Челябинск Издательство ЮУрГУ 2009 УДК 54(075.8) ББК Ш143.21-923 Д182 Одобрено учебно-методической комиссией химического факультета Рецензенты: Балыкин В.П., Бояльская Т.А. Д182 Данилина, Е.И. Химия на английском языке. Модуль 1. Базовые химические понятия: учебное пособие. – Челябинск: Изд-во ЮУрГУ, 2008. – 37 с. Учебное пособие составлено на английском языке по материалам американских и английских учебников по химии для колледжей и университетов и предназначено для практических занятий и самостоятельной работы студентов. В учебном пособии предложены вопросы и задачи, охватывающие круг базовых химических понятий и соответствующие школьному курсу химии. В приложениях приведены необходимые справочные материалы для численного решения задач и их устного чтения: Периодическая таблица, транскрипция названий элементов и соединений по правилам ИЮПАК. Пособие предназначено для студентов 1 курса химического факультета. УДК 54(075.8) ББК Ш143.21-923 © Издательство ЮУрГУ, 2009 2 CONTENTS 1. Formulas and Names of Elements and Compounds..........................................4 2. Atomic and Molecular Mass. Mole Concept......................................................9 3. Calculating the Percentage by Mass.................................................................14 4. Concentration of Solutions...............................................................................18 5. Balancing Chemical Equations.........................................................................21 6. Calculations Based on Chemical Equations......................................................25 References.............................................................................................................30 Appendix 1. Periodic Table of Chemical Elements..............................................31 Appendix 2. Elements and Electronegative Components.....................................33 Appendix 3. Acids and Anions..............................................................................36 3 1. FORMULAS AND NAMES OF ELEMENTS AND COMPOUNDS 1.1. What is the chemical symbol for each of the following elements? a) iron; b) silver; c) phosphorus; d) calcium: e) mercury; f) nickel. 1.2. What are the symbols for the following elements? a) magnesium; b) manganese: c) cobalt: d) argon: e) silicon; f) beryllium. 1.3. What is the name of each of the following element? a) K; b) Al; c) C; d) N; e) Ne; f) Na; g) O; h) Os; i) He. 1.4. Give the names of the elements for which the symbols are… a) H; b) Rb; c) Ba; d) Sr; e) S; f) Xe; g) F; h) Cl; i) Bi. 1.5. What are the empirical formulas of each of the following? a) N2O4; b) C6H12O6; c) C8H8; d) CH3COOH. 1.6. The structural formula for glucose is H H OH O HO C H H H C OH H H C OH OH H O H C OH CH2OH H C H CH2OH OH What are the molecular and empirical formulas of glucose? 1.7. Choose the elements that form monoatomic anions from the following list; name the elements and the anions: Zn, H, Al, S, K, Hg, F, Ag, I, Sb, Cu, V, P, Cl, Na, Si, He, Cs, Br, Cr, N, Fe, Pb, Cd, C, W, Ne, Zr. 4 1.8. How are the cations named in compounds? (Pay attention to Roman numerals.) +1 Li+ Na+ K+ Ag+ Cu+ Hg+ NH4+ +2 Mg2+ Ca2+ Ba2+ Zn2+ Ni2+ Fe2+ Cu2+ Hg2+ Pb2+ Sn2+ Co2+ +3 Al3+ Bi3+ Cr3+ Fe3+ Co3+ +4 Pb4+ Sn4+ 1.9. What are the symbols of the following monoatomic anions? –1 bromide chloride fluoride hydride iodide –2 –3 oxide peroxide sulfide nitride phosphide 1.10. Name the following compounds: a) MgCl2; b) AlBr3; c) Li3N; d) CaO; e) CaS; f) Al2O3. 1.11. Name the following compounds: a) CrCl3; b) CuO; c) Mn2O3; d) SnO2; e) Hg2Cl2; f) PbS; g) FeCl3; h) PbI2; i) Pb3O4. 1.12. Write the formulas of the following compounds: a) calcium chloride; b) zinc sulfide; c) strontium fluoride; d) magnesium oxide; e) silver bromide; f) barium chloride; g) mercury(I) iodide; h) tin(IV) chloride. 1.13. Write the chemical formulas for the following compounds: a) sodium oxide; b) barium sulfide; c) magnesium nitride; d) silver iodide; e) calcium carbide; f) iron(III) chloride. 5 1.14. Write the formulas of the following compounds: a) magnesium bromide; b) aluminum carbide; c) copper(I) chloride; d) barium iodide; e) silver nitride; f) zinc fluoride. 1.15. Supply the missing information about the following compounds: a) SnF2; e) iron(III) sulfide; b) FeS; f) tin(IV) chloride; c) PbO2; g) lead(II) oxide; d) CuBr2; h) chromium(III) chloride. 1.16. Name the following compounds; a) ICl3; b) BrF3; c) AsCl3; d) SF4; e) PCl3; f) SO3. 1.17. Write correct chemical formulas for the following: a) chlorine dioxide; b) silicon tetrafluoride; c) diboron tetrabromide; d) tricarbon disulfide; e) iodine pentafluoride; f) tetraphosphorus trisulfide. 1.18. Write the chemical formula of each of the following compounds: a) dinitrogen tetroxide; b) sulfur hexafluoride; b) bromine trifluoride; c) tetraphosphorus decoxide; d) sulfur dioxide; e) phosphorus pentachloride. 1.19. Give the name of the following compounds: a) KCl; b) Na2S; c) NaI; e) P4O6; f) N2O3. d) SO3; 1.20. Write down the names for the following polyatomic anions: –1 OH– NO3– MnO4– ClO3– HCO3– CH3COO– IO3– CN– –2 SO42– CO32– CrO42– Cr2O72– C2O42– SO32– S2O32– 6 –3 –4 PO43– Fe(CN)63– SiO44– Fe(CN)64– 1.21. Write the correct formula name them: a) Al3+ and O2–; c) Pb2+ and O2–; e) NH4+ and SO42–; g) Fe3+ and OH–; of compounds formed between the following ions, b) Mg2+ and N3–; d) NH4+ and CN–; f) Al3+ and SO42–; h) Fe2+ and OH–. 1.22. Write the chemical formulas for the following compounds: a) magnesium nitrate; b) silver nitrate; c) ammonium chromate; d) potassium phosphate; e) nickel(II) chlorate; f) copper(I) bromide; g) zinc phosphate; h) chromium(III) sulfate; i) calcium carbonate; j) potassium permanganate; k) lead(II) acetate; l) aluminum hydroxide. 1.23. Write correct formulas for the following compounds: a) iron(III) sulfide; b) mercury(I) acetate; c) ammonium nitrate; d) calcium bicarbonate; e) lead(II) chromate; f) potassium permanganate. 1.24. Write the correct formula of the compounds formed between the corresponding cations and anions, name them: Ions Na+ Ca2+ Al3+ Cl– O2– PO43– SiO32– OH– NO3– 1.25. Give the names of the following compounds: a) CuSO4; b) Mg3(PO4)2; c) BaCrO4; d) K2Cr2O7; e) S2Cl2; f) SCl6; g) SnBr4; h) Cl2O7; i) MgSO4·7H2O; j) CaSO4·2H2O. 1.26. Name the compounds which contain polyatomic ions: a) NaNO3; b) SrCO3; c) Ca3(PO4)3; d) KClO3; e) Al2(SO4)3; f) K2Cr2O7. 1.27. Write the correct names for the following salts: a) CuI; b) CuI2; c) SnCl2; d) SnCl4; e) CoSO4; f) Co2(SO4)3. 7 SO42– S2– 1.28. Write the correct formulas of the compounds formed between the corresponding cations and anions: Oxide Iodide Phosphate Permanganate Sulfide Hydroxide Chromate Carbonate Sodium Silver Zinc Ammonium Copper(I) Iron(II) Iron(III) Lead(IV) Sodium Silver Zinc Ammonium Copper(I) Iron(II) Iron(III) Lead(IV) 1.29. Supply the missing information for each of the following: a) PbCrO4; b) dihydrogen monoxide; c) (NH4)2Cr2O7; d) sodium thiosulfate; . e) MgCl2 6H2O; f) potassium ferricyanide; g) P4O6; h) sodium sulfate decahydrate; i) CBr4; j) phosphorus tribromide. 1.30. Supply the missing information for the following compounds: a) KMnO4; b) sodium nitrate; c) FePO4; d) silver phosphate; . e) FeSO4 7H2O; f) cobalt(II) sulfate; g) Si2F6; h) lead(IV) acetate; i) Cl2O; j) potassium carbonate. 1.31. Supply the missing information for the following: a) (NH4)2SO4; b) sodium chromate; c) NaOH; d) calcium cyanide; e) Cu3(PO4)2; f) potassium chlorate; g) Al2(CO3)3; h) potassium oxalate; i) Pb(IO3)2; j) chromium(III) nitrate. 8 2. ATOMIC AND MOLECULAR MASS. MOLE CONCEPT 2.1. The ratio of the mass of oxygen to carbon atom is 1.3329. What is the mass of the oxygen atom? 2.2. The ratio of the mass of bromine atom to carbon is 6.650. What is the mass of the bromine atom? 2.3. Calculate the number of moles in each of the following: a) 3.01x1022 N2 molecules; b) 4.82x1024 iron atoms. 2.4. Perform the following interconversions of mole and partical number: a) 6.02x1022 Fe atoms = ? mol Fe atoms; b) 2 mol O2 molecules = ? O2 molecules; c) 1.2x1025 H2O molecules = ? mol H2O molecules; d) 0.25 mol H+ ions = ? H+ ions. 2.5. How many years does it take to evaporate all the molecules in one millimole of water, if six billion (6x109) water molecules evaporate in each second? 2.6. Answer these questions for 0.25 mol of Al2O3. Find: a) the number of molecules it contains; b) the mole number of each kind of atom it contains; c) the total number of atoms it contains. 2.7. Answer these questions for 2.4x1024 SO3 molecules. Find: a) its mole number; b) the number of moles of S and O atoms it contains; c) the total number of atoms it contains. 2.8. Answer these questions for 26 g of chromium. Calculate: a) the mole number of atoms it contains; b) the number of atoms it contains; c) the mass of a single chromium atom (pay attention to the differences between atomic mass and the actual mass of an atom). 2.9. How many grams of each of the constituent elements are contained in one mole of: a) CH4; b) Fe2O3; c) Ca3P2? How many atoms of each element are contained in the same amount of compound? 2.10. Calculate the number of grams in a mole of each of the following common substances: a) calcite, CaCO3; b) quartz, SiO2; 9 c) cane sugar, C12H22011; d) gypsum, CaSO4.2H2O; e) white lead, Pb(OH)2. 2.11. Calculate the molar mass of each of these compounds: a) CO2; b) Ca3(PO4)2; c) CuSO4·5H2O; d) Fe(NH4)2(SO4)2 ·6H2O. 2.12. Calculate the molar mass of the following compounds: a) N2O5; b) H2SO4; c) Al(OH)3; d) KAl(SO4)2·12H2O; e) Fe4[Fe(CN)6]3. 2.13. What is the mass of 1.00 mole of each of the following nitrogen compounds: N2O; NO; NO2; NH3; N2H4; HN3? 2.14. Determine the molar mass for: a) LiOH; b) H2SO4; c) O2; d) S8; e) Ca3SO4; f) K4[Fe(CN)6]. 2.15. Perform the following conversions: a) 3.2 g Cu = ? mol Cu; b) 0.2 mol Ag = ? g Ag; c) 3.01x1022 Fe atoms = ? mol Fe atom = ? g Fe; d) 1 silver atom = ? g; e) 6.4 g S atom = ? mol S atom = ? S atoms. 2.16. List the following species in order of increasing mass: a) 1 mol C atom; b) 1 g of C; c) 1 carbon atom; d) 3.01x1023 C atoms. 2.17. Which one of the following is the heaviest? a) 3.02x1023 Mg atoms; b) 0.2 mol S atom; c) 10.8 g of Ag; d) 1 mol Li. 2.18. How many moles of atoms are contained in: a) 32.7 g Zn; b) 7.09 g C1; c) 95.4 g Cu; d) 4.31 g Fe; e) 0.378 g S? 2.19. Calculate, how many moles are represented by: a) 24.5 g H2SO4; b) 4.00 g O2. 10 2.20. For the compound Cd(NO3)2⋅4H2O, calculate: a) how many moles of Cd and of N are contained in 132.4 g of it; b) how many molecules of water of hydration are in this same amount. 2.21. How many moles and grams of Fe and of S are contained in: a) 1 mol of FeS2 (pyrite); b) exactly 1 kg of FeS2. 2.22. A certain public water supply contained 0.10 ppb (part per billion) of chloroform, CHC13. How many molecules of CHC13 would be contained in a 0.05-mL drop of this water? 2.23. Find the number of molecules in: a) 25.0 g of H2O; b) 1.00 kg of sugar, C12H22O11; c) 1.00 microgram of NH3; d) 5.00 mL of CCl4 whose density is 1.594 g/mL. 2.24. Determine the number of molecules in: a) 50.0 g of mercury; b) 0.500 kg of glucose C6H12O6; c) 1.00 nanogram of HCl; d) 25.0 mL of benzene, C6H6, whose density is 0.879 g/mL. 2.25. Calculate the mole number of each of the following compounds: a) 15.2 g N2O3; b) 17.1 g Al2(SO4)3; c) 87.6 g CaCl2·6H2O. 2.26. Perform the following conversions: a) 8.8 g NaOH = ? mol NaOH; b) 0.05 mol Ca3(PO4)2 = ? g Ca3(PO4)2; c) 2.4x1023 H2O molecules = ? mol H2O = ? g H2O; d) 17.16 g Na2CO3·10H2O = ? mol Na2CO3·10H2O = ? Na2CO3·10H2O molecules. 2.27. These problems refer to dinitrogen pentoxide, N2O5. a) Calculate the molar mass. b) Find the mass of 1.25 mol N2O5. c) How many moles of N2O5 are there in 5.4 g of compound? d) Calculate the mass of compound that contains 0.5 mol of oxygen atom. e) Calculate the mass of compound that contains 6.4 g of oxygen. f) Find the mass of N combined with 32 g of oxygen. 11 g) Calculate the number of N atoms in 21.6 g of N2O5. 2.28. Answer the following questions for CO2. Find: a) its molar mass; b) the mass of 1.25 mol of CO2; c) the mole number in 17.6 g of compound; d) the number of molecules in 6.6 g of CO2; e) the mass of C combined with 0.25 mol O; f) the mol number of O combined with 2.4 g C; g) the number of O atoms in 35.2 g CO2; h) the number of C atoms combined with 20 oxygen atoms. 2.29. 3 mol mixture of SO2 and CO gases weighs 120 g. Find the mole number of each gas in the mixture. 2.30. What is the volume of each of the following gases at standard temperature and pressure (STP)? a) 9.25 mol SO2; b) 35.2 g CO2; c) 1.2x1024 H2 molecules. 2.31. Perform these conversions: a) 2 mol N2 = ? L (at STP); b) 6.8 g NH3 = ? L (at STP); c) 5.6 L O2 at STP = ? mol O2 = ? g O2 = ? O2 molecules; d) 4.8x1022 H2 molecules = ? mol H2 = ? L H2 = g H2. 2.32. How many atoms of nitrogen are there in 0.1 mol of Ca(NO3)2? 2.33. How many grams of Ca(NO3)2 would you need to get 1.00 gram of calcium? 2.34. What is the mass of (NH4)2SO4 that contains Avogadro's number of hydrogen atoms? 2.35. How many N2O5 molecules are there in 1.08 g of N2O5? 2.36. How many molecules are there in 5.6 L CO2 at STP? 2.37. How many (a) grams of H2S, (b) moles of H and of S, (c) grams of H and of S, (d) molecules of H2S are contained in 0.400 mol H2S? 2.38. Answer the following questions for P2O5 that contains 0.62 g of phosphorus. a) Find the mole number of P2O5. b) Find the number of molecules of P2O5. 12 c) Find the mass of O in the compound. d) Find the total number of atoms in the compound. 2.39. 0.02 mol of unknown compound Y2O5 weighs 2.16 g. Calculate: a) the molar mass of the compound; b) the atomic mass of the element, Y; c) the mass of a single Y atom. 2.40. 0.05 mol of an unknown compound X(ClO3)2 is 15.2 g. Find the atomic mass and the mass of a single X atom. 2.41. 3.42 g X2(SO4)3 contains 0.12 mol of oxygen atoms. What is the atomic mass of X? 2.42. 104.8 g of Mg3(YO4)2 contains 0.8 mol of Y. What is the atomic mass of Y? 2.43. 35.7 g of Cr2(X2O4)3·6H2O contains 8.1 g H2O. What is the atomic mass of X? 2.44. 10.4 g of X combine with oxygen to form 15.2 g of X2O3. What is the atomic mass of X? 2.45. When 1.92 g Y is heated with aluminum, 3 g of Al2Y3 are formed. What is the atomic mass of Y? 2.46. 0.25 mol of CnH2n–2 contains 1.5 mol of H atoms. What is the molar mass of the compound? 2.47. 0.5 mol compound with a general formula CnH2n+2 contains 3 mol of H. Find the molar mass of the compound. 2.48. A sample weighing 42.6 g of NX3 occupies 13.44 L at STP. Find the atomic mass of the element X. 2.49. Find the atomic mass of X in each of the following problems. a) The mass of a single X atom is 1.5 x 10–23 g. b) 2.4 x 1023 molecules of XCl2 is 44.4 g. c) 5.6 L of XH3 at STP is 8.5 g. d) 0.4 mol PX3 and 0.6 mol PX5 weigh 367 g. c) 3.84 g Li2SiX6·2H2O contains 0.72 g H2O. 13 3. CALCULATING THE PERCENTAGE BY MASS 3.1. Calculate the percentages of oxygen and hydrogen in water H2O. 3.2. What is the percentage by mass of each element in Al2(SO4)3? 3.3. What are the percentages of boron and water in borax, Na2B4O5(OH)4·8H2O? 3.4. Calculate the percentages of elements K, Fe, C, N, and H2O in K4[Fe(CN)6]·3H2O crystals. 3.5. Which of these fertilizers has the highest percentage by mass of nitrogen? a) Urea, N2H4CO. b) Ammonium nitrate, NH4NO3. c) Ammonium phosphate (NH4)3PO4. 3.6. Find the percentage by mass of nitrogen in each of the following compounds: a) N2O; b) NO; c) NO2; d) NH3; e) N2H4; f) HN3. 3.7. Find the percentage by mass of sodium and sulfur in the following sodium salts: a) Na2SO4; b) Na2S2O3; c) Na2SO4·10H2O; d) Na2S2O3·5H2O. 3.8. Determine the percentage composition of potassium carbonate (the percentage composition = the percentage by mass of each element). 3.9. Calculate the percentage composition of the following compounds: a) Ca(CN)2; b) (NH4)2CO3; c) UO2(NO3)2·6H2O; d) C16H26O4N2S (penicillin). 3.10. Find the percentage composition of the following compounds: a) (NH4)2CrO4; b) PtP2O7; c) BiONO3·H2O; d) C21H29O12N7 (streptomycin). 3.11. A sample of a compound contains 18.02 g C, 2.52 g H, 3.50 g N, 4.00 g O and 8.02 g S. What is the percentage by mass of each element in the compound? 3.12. A sample having a mass of 0.924 g was decomposed into its components and found to have 0.389 g of carbon, 0.059 g of H and 0.476 g of O. Find the percentage composition of this substance. 3.13. What is the empirical formula of a compound consisting of 7.8 g of potassium, 7.1 g of chlorine and 9.6 g of oxygen? 14 3.14. A borane (containing only B and H) contained 88.45 % B. What is its empirical formula? 3.15. When 10.24 g of Cu is heated in an atmosphere of oxygen, 11.52 g of an oxide of copper is produced. What is the empirical formula of the oxide formed? 3.16. A 2.522 g sample of pure caffeine contains 1.248 g of carbon, 0.130 g of hydrogen, 0.728 g of nitrogen and 0.416 g of oxygen. What is the simplest formula of caffeine? If the molar mass of caffeine is 194, what is its molecular formula? 3.17. Cocaine is 67.30 % C, 6.98 % H, 21.10 % O, and 4.62 % N. What is the simplest formula of cocaine? 3.18. What is the simplest formula of the compound that shows the following analysis: 44.83 % potassium, 18.39 % sulfur, 36.78 % oxygen? 3.19. From the following analytical results (percentage by mass), determine the empirical formulas for the compounds analyzed: a) 42.9% C, 57.1% O; b) 77.7% Fe, 22.3% O; c) 27.3% C, 72.7% O; d) 70.0% Fe, 30.0% O; e) 53.0% C, 47.0% O; f) 72.4% Fe, 27.6% O. 3.20. Find the empirical formulas of the salts with the following percentage by mass: a) 40.2% K, 26.9% Cr, 32.9% O; b) 26.6% K, 35.4% Cr, 38.0% O; c) 19.3% Na, 26.8% S, 53.9% O; d) 29.1% Na, 40.5% S, 30.4% O; e) 32.4% Na, 22.6% S, 45.0% O. 3.21. Determine the empirical formula for each of the compounds: a) 21.8% Mg, 27.9% P, 50.3% O; b) 66.8% Ag, 15.9% V, 17.3% O; c) 79.3% Tl, 9.9% V, 10.8% O; d) 25.8% P, 26.7% S, 47.5% F; e) 19.2% P, 2.5% H, 78.3% I; f) 52.8% Sn, 12.4% Fe, 16.0% C, 18.8% N; g) 14.2% Ni, 61.3% I, 20.2% N, 4.3% H. 3.22. A compound has the following percentage composition by mass: 58.8 % C, 9.8 % H, and the remainder is oxygen. a) Calculate the empirical formula of the compound. b) If 0.2 mol of the compound weighs 40.8 g, find its molecular formula. 15 3.23. What are the empirical formulas of the compounds with the following composition: a) 38.71 % C, 16.13 % H, and 45.16 % N; b) 26.53 % K, 35.37 % Cr, the remainder is oxygen; c) 21.8 % Mg, 27.8 % P, and 50.3 % O; d) 79.1 % CaSO4, 20.9 % H2O; e) 37.7 % Na, 22.95 % Si, the remainder is oxygen. 3.24. A given compound consists of 6.02x1022 atoms of carbon, 1.806x1023 atoms of hydrogen and 6.02x1022 atoms of oxygen. What is its simplest formula? 3.25. The analysis of a compound showed that it contained 7.2 g carbon, 1.2 mol hydrogen, and 3.6x1023 atoms of oxygen. What is the molecular formula of the compound, if its molar mass is 180 g/mol? 3.26. Pyrex glass typically contains 12.9 % B2O3, 2.2 % Al2O3, 3.8% Na2O, 0.4 % K2O, and 80.7 % SiO2. What is the ratio of silicon to boron atoms in the glass? 3.27. Weighed samples of the following hydrates are heated to drive off the water, and then the cooled residues are weighed. From the data given, find the formulas of the hydrates: a) 0.695 g of CuSO4 ⋅ xH2O gave a residue of 0.445 g; b) 0.573 g of Hg(NO3)2 ⋅ xH2O gave a residue of 0.558 g; c) 1.205 g of Pb(C2H3O2)2 ⋅ xH2O gave a residue of 1.032 g; d) 0.809 g of CoCl2 ⋅ xH2O gave a residue of 0.442 g; e) 2.515 g of CaSO4 ⋅ xH2O gave a residue of 1.990 g; f) 0.520 g of NiSO4 ⋅ xH2O gave a residue of 0.306 g; g) 0.895 g of MnI2 ⋅ xH2O gave a residue of 0.726 g; h) 0.654 g of MgSO4 ⋅ xH2O gave a residue of 0.320 g; i) 1.216 g of CdSO4 ⋅ xH2O gave a residue of 0.988 g; j) 0.783 g of KAl(SO4)2 ⋅ xH2O gave a residue of 0.426 g. 3.28. When 3 g of Mg is burned in excess oxygen, it produces 5 g of magnesium oxide. What is the empirical formula of the oxide formed? 3.29. When 5.8 grams of silver oxide are decomposed, there remains a silver residue of 5.4 grams. Calculate the simplest formula of silver oxide. 3.30. The elemental analyses of several compounds are given below. Determine the empirical formula of each compound whose composition is shown below: a) 5.6 g Fe and 2.4 g O; b) 0.64 g S and 0.64 g O; 16 c) 2.82 g K, 2.56 g Cl, 4.62 g O; d) 18 g C, 1.65 g H, 2.10 g N and 2.4 g O; e) 4 g Ca, 6.02x1022 C atoms, 0.3 mol O; f) 2.78 g Co, 11.96 g I, and 4.52 g O. 3.31. A compound with a known molar mass of 28 contains 85.71% carbon and 14.29 % hydrogen. Find its molecular formula. 3.32. A sample of a compound is found to contain 0.97 grams of phosphorus and 1.25 grams of oxygen. If 0.02 mol of this compound weighs 5.68 g, calculate its molecular formula. 3.33. An element X forms four oxides containing 77.4, 63.2, 69.6, and 72.0 % X. If the compound with 77.4 % X is XO, what is X, and what are the empirical formulas of the other compounds? 3.34. A metal forms two different chlorides. Analysis shows one to be 51.1% Cl and the other to be 64.4% Cl by mass. What are the possible values of the atomic mass of the metal? 3.35. A metal forms two different chlorides. Analysis shows one to be 40.3% metal and the other to be 47.4% metal by mass. What are the possible values of the atomic mass of the metal? 3.36. A sample of an organic compound containing C, H, and O, which weighs 12.13 mg, gives 30.6 mg of CO2 and 5.36 mg of H2O in combustion. The amount of oxygen in the original samples is obtained by difference. Determine the empirical formula of this compound. 3.37. An organic compound containing C, H, O, and S is subjected to two analytical procedures. When a 9.33 mg sample is burned, it gives 19.50 mg of CO2 and 3.99 mg of H2O. A separate 11.05 mg sample is fused with Na2O2, and the resulting sulfate is precipitated as BaSO4, which (when washed and dried) weighs 20.4 mg. The amount of oxygen in the original sample is obtained by difference. Determine the empirical formula of this compound. 3.38. A 5.135 g sample of impure limestone (CaCO3) yields 2.050 g of CO2 (which was absorbed in a soda-lime tube) when treated with an excess of acid. Assuming the limestone is the only component that would yield CO2, calculate the percentage purity of the limestone sample. 17 4. CONCENTRATION OF SOLUTIONS 4.1. A salt-water solution is prepared by dissolving 20 g NaCl in 230 g of water. What is the percentage by mass of salt in the solution? 4.2. Calculate the percentage by mass of solute in a solution prepared by dissolving 20 g sugar in 60 g of water. 4.3. Suppose that you have 160 g of a solution that is 20% sugar by mass. Calculate the percentage concentration of the new solution resulting after: a) it is mixed with 40 g of water; b) 32 g of water is evaporated from the original solution; c) it is mixed with 40 g of sugar; d) it is mixed with 40 g water and 40 g of sugar; e) it is mixed with 840 g of a solution containing 5 % sugar. 4.4. Calculate the amount (g) of NaOH in 800 g solution that is 20 % NaOH by mass. 4.5. Calculate the percentage concentration of the solution resulted by mixing 150 g solution that is 20% sugar by mass, 50 g solution that is 30 % sugar by mass, 85 g water and 15 g of sugar. 4.6. How much NaCl must be added to 150 g of 10 % NaCl solution so that the percentage of NaCl in the resulting solution is 20 %. 4.7. Calculate the masses of 20% and 40% sugar solutions that must be mixed to obtain 400 g of solution containing 25 % sugar by mass. 4.8. Concentrated nitric acid solution has density of 1.42 g/mL and contains 72% HNO3 by mass. How many grams of HNO3 are there in 500 mL of this concentrated solution? 4.9. A student needs 109.5 g of HCl for a reaction. What volume of concentrated hydrochloric acid solution with a density of 1.2 g/mL and containing 36.5 % HCl by mass contains 109.5 g of HCl? 4.10. Describe how to prepare 500 mL of 1.5 M Na2SO4 solution. 4.11. 30 g NaOH is dissolved in enough water to form 600 mL of solution. What is the molarity of the solution? 4.12. 11.2 liters of NH3 gas measured at STP is dissolved in water to prepare 5 liters of solution. Calculate the molarity of the solution. 18 4.13. Calculate the molarity of the following solutions: a) 5 L solution containing 2 mol BaCl2; b) 250 mL solution containing 7 g of KOH; c) 500 mL solution containing 6.02x1022 NH3 molecules; d) 500 mL solution containing 28.75 mL C2H5OH (d = 0.8 g/mL); e) 600 mL solution containing 6.72 L HCl measured at STP; f) 1250 mL solution containing 42.5 g of NaNO3 sample that is 80% pure. 4.14. How many grams of Fe(NO3)2 are required to make 400 mL of a solution with concentration 0.5 M Fe(NO3)2? 4.15. How many liters of 3 M NaOH solution can be prepared with 360g NaOH? 4.16. Describe how to prepare 0.2000 M CuSO4, starting with solid CuSO4⋅5H2O. 4.17. Tell how you would prepare each of the following solutions: a) 3.00 liters of 0.750 M NaCl from solid NaCl; b) 55.0 mL of 2.00 M ZnSO4 from solid ZnSO4⋅7H2O; c) 180 mL of 0.100 M Ba(NO3)2 from solid Ba(NO3)2; d) 12 liters of 6.0 M KOH from solid KOH; e) 730 mL of 0.0700 M Fe(NO3)3 from solid Fe(NO3)3⋅9H2O. 4.18. Tell how you would prepare each of the following solutions: a) 125 mL of 0.62 M NH4Cl from solid NH4Cl; b) 2.75 liters of 1.72 M Ni(NO3)2 from solid Ni(NO3)2⋅6H2O; c) 65.0 mL of 0.25 M Al(NO3)3 from solid Al(NO3)3⋅9H2O; d) 230 mL of 0.460 M LiOH from solid LiOH; e) 7.57 liters of 1.10 M KCr(SO4)2 from solid KCr(SO4)2⋅12H2O. 4.19. 500 mL of water are added to 300 mL of 0.4 M H2SO4 solution. Find the molarity of the resulting solution. 4.20. 100 mL of 6 M HCl solution is diluted to 600 mL. What is the molar concentration of the final solution? 4.21. What volume of water must be added to 200 mL of 3 M BaCl2 solution to obtain 1 M solution? 4.22. How many mL of water must be evaporated from 500 mL of 0.3M NaCl solution so that the concentration of NaCl becomes 0.5 M? 19 4.23. Describe how you would prepare 2 L of 0.7 M HNO3 solution, starting with a concentrated HNO3 solution that has a density of 1.4 g/mL and contains 63 % HNO3 by mass. 4.24. Commercial concentrated sulfuric acid is labeled as being 96.0% H2SO4 by mass and having a density of 1.84 g/mL. Calculate the molarity of this solution. 4.25. The density of a 3.68 M sodium thiosulfate solution is 1.269 g/mL. Find the percentage of Na2S2O3 by mass. 4.26. The density of a 1.660 M Na2Cr2O7 solution is 1.244 g/mL. a) Find the percentage of Na2Cr2O7 by mass. b) If 1.50 liters of water are added to 1.0 liter of this solution, what is the percentage by mass of Na2Cr2O7 in the new solution? 4.27. The density of a 2.04 M Cd(NO3)2 solution is 1.382 g/mL. If 500 mL of water is added to 750 mL of this solution, what will be the percentage by mass of Cd(NO3)2 in the new solution? 4.28. How many mL of 0.5 M H2SO4 solution can be prepared from 20 mL of 2.5 M H2SO4 solution? 4.29. A 300 mL of 0.2 M HNO3 solution is added to 200 mL of 0.15 M HNO3 solution. Calculate the molarity of the resulting solution. 4.25. 400 mL of 0.6 M KCl solution is added to 600 mL of 0.2 M KCl solution. What is the molarity of the final solution? 4.26. If 500 mL of 3.00 M H2SO4 is added to 1.50 liters of 0.500 M H2SO4, what is the resulting concentration? 4.27. What volumes of 2 M and 6 M solutions of HCl should be mixed to prepare 500 mL of a 3 M solution? Disregard the change in the volume in mixing. 4.28. What volumes of 4 M and 6 M KNO3 solutions should be mixed to obtain a 500 mL of 4.8 M KNO3 solution? 4.29. 3.1 g MgX2 is used to prepare 500 mL of 0.1 M MgX2 solution. What is the atomic mass of X? 4.30. 19.36 g of X(NO3)3 is used in the preparation of 400 mL of 0.2 M solution. Calculate the atomic mass of X. 20 5. BALANCING CHEMICAL EQUATIONS 5.1. In laboratory, oxygen gas may be generated by decomposing potassium chlorate (KClO3) into potassium chloride and oxygen gas. Write a balanced equation describing the reaction. 5.2. Water that contains dissolved calcium compounds is called "hard" water. One way to "soften" such water is to add sodium carbonate, Na2CO3. It removes the calcium by forming calcium carbonate, which is insoluble in water. Balance the equation that illustrates the reaction. 5.3. Consider the combustion of amyl alcohol, C5H11OH. a) How many moles of O2 are needed for the combustion of 1 mole of amyl alcohol? b) How many moles of H2O are formed for each mole of O2 consumed? c) How many moles of CO2 are produced for each mole of amyl alcohol burned? 5.4. Balance each of the following equations: a) CH4 + Cl2 → CCl4 + HCl; b) C2H6 + O2 → CO2 + H2O; c) Al(OH)3 + H2SO4 → Al2(SO4)3 + H2O; d) P2H4 → PH3 + P4; e) Fe + H2O → Fe3O4 + H2; f) S2Cl2 + NH3 → N4S4 + NH4Cl + S8; g) Al4C3 + HCl → AlCl3 + CH4; h) Ag + HNO3 → AgNO3 + NO + H2O. 5.5. Balance the following equations: a) C2H4(OH)2 + O2 → CO2 + H2O; b) Li + H2O → LiOH + H2; c) Ba(OH)2 + AlCl3 → BaCl2 + Al(OH)3; d) KHC8H4O4 + KOH → K2C8H4O4 + H2O; e) (NH4)2Cr2O7 → N2 + Cr2O3 + H2O. 5.6. What is the molecular formula of the compound represented by X in the following balanced equation? 4 X + 5 O2 = 4 NO + 6 H2O 5.7. Determine the formula of X in the following balanced equations: a) 9 Fe2O3 + 2 NH3 = 6 X + N2 + 3 H2O; b) 2 MnO2 + 4 X + O2 = 2 K2MnO4 + 2 H2O; c) 2 KMnO4 + 16 HCl = 2 MnCl2 + 2 KCl + 5 X + 8 H2O; 21 d) Cr2O3 + 3 X = 2 CrCl3 + 3 CCl2O; e) As2S3 + 12 NaNO3 + 3 Na2CO3 = = X + 3 Na2SO4 + 3 CO2 + 12 NaNO2. 5.6. Predict the products of the following reactions and balance the equations: a) HCl + Mg(OH)2 → … b) PbCl2 + K2SO4 → … c) CH3CH2OH + O2 → … d) Fe + AgNO3 → … 5.7. Given that the oxidation state of hydrogen is “+1”, of oxygen “–2”, and of fluorine “–1”, determine the oxidation states of the other elements in: a) NaF; b) H2SiO3; c) PH3; d) H2S; e) CrF3; f) H2SO4; g) H2SO3; h) Al2O3; i) HPO42–. 5.8. Determine the oxidation number of the central atom in: a) K4P2O7; b) NaAuCl4; c) Na5HV10O28; d) ICl; e) Ba2XeO6; f) Ca(ClO2)2. 5.9. Find the oxidation number of each atom in the following molecules and ions: a) CO2; b) AgNO3; c) BaO2; d) LiH; e) Ca2P2O7; f) C2O42–; g) PCl62–; h) B4O72–; i) UO22+. 5.10. Find the oxidation number of each atom in the following molecules and ions: a) SO3; b) H2SO3; c) Zn(IO3)2; d) Na2O2; e) (NH4)2PO4; f) V2O72–; g) BiO+; h) SiO32–; i) S2O32–. 5.11. Write balanced ionic half-reactions for the oxidation of each of the following reducing agents in acid solution: a) Sn; b) H2C2O4; c) Br–; d) Sn2+; e) H2S; f) Ba; g) Al; h) HNO2; i) Hg22+; j) I–; k) H3AsO3; l) H2O2. 5.12. Write balanced ionic half-reaction equations for the reduction of each of the following oxidizing agents in acid solution: a) Co3+’ b) PbO2; c) ClO4–; d) F2; e) Ag+; f) NO3–; g) BrO–; h) Sn2+; i) MnO2; j) ClO2–; k) H2O2; l) Cr2O72–; m) IO3–; n) Br2; o) Fe2+; p) Cd2+. 22 5.13. Balance the oxidation-reduction equations: a) NaBr + Cl2 → NaCl + Br2; b) Sn + O2 + HCl → SnCl2 + H2O; c) FeCl2 + H2O2 + HCl → FeCl3 + H2O. 5.14. Balance the oxidation-reduction equation for the oxidation of H2S by HNO3 to produce NO and S in aqueous acidic solution (thus H+ and H2O may be involved). 5.15. Balance the oxidation-reduction equation for the oxidation of FeCl2 by Na2Cr2O7 to give CrCl3 and FeCl3 in aqueous acidic solution. 5.16. Balance the oxidation-reduction equation for the oxidation of Zn by NaNO3 to produce Na2Zn(OH)4 and NH3 in basic aqueous solution. 5.17. Balance the following equations, describing oxidation by nitric acid: a) Cu + HNO3 (conc.) → Cu(NO3)2 + NO2 + H2O; b) Cu + HNO3 (dilute) → Cu(NO3)2 + NO + H2O; c) Zn + HNO3 (dilute) → Zn(NO3)2 + NH4NO3 + H2O; d) CuS + HNO3 → Cu(NO3)2 + S + NO + H2O; e) As2S5 + HNO3 → H3AsO4 + H2SO4 + NO2. 5.18. Balance the following skeleton equations (acidic aqueous solutions), complete molecular reactions: a) MnO + PbO2 → MnO4– + Pb2+; b) C2O42– + MnO4– → CO2 + Mn2+; c) H2O2 + MnO4– → Mn2+ + H2O. 5.19. Balance the following equations (basic aqueous solutions): a) Bi2O3 + NaOH + NaOCl → NaBiO3 + NaCl; b) Fe(CN)63– + Cr2O3 → Fe(CN)64– + CrO42–; c) CrI3 + Cl2 → CrO42– + IO4– + Cl–; d) Ag + CN– + O2 → Ag(CN)2– + OH–; e) Co2+ + Na2O2 → Co(OH)3↓. 5.20. Balance the following equations (no water involved): a) NaN3 → Na3N + N2; b) Ca3PO4 + SiO2 + C → CaSiO3 + P4 + CO; c) P2H4 → PH3 + P4H2. 5.21. Write balanced equations for the reaction that occurs between metallic zinc and dilute nitric acid to produce ammonium nitrate as one of the products. 23 5.22. When sodium thiosulfate, Na2S2O3, interacts with iodine in quantitative analysis, one of the products is sodium tetrathionate, Na2S4O6. Write the complete equation and balance it. 5.23. A sample of potassium iodide contains some potassium iodate as impurity. When sulfuric acid is added to a solution of this sample, iodine is produced. Give the equation for the formation of the iodine. 5.24. When copper is heated in concentrated sulfuric acid, an odor of sulfur dioxide is noted. Write the chemical equation; balance it. 5.25. A classical operation in quantitative analysis is the use of a Jones reductor, a column of granulated zinc. A solution of ferric (Fe3+) salts is passed through this column prior to titration with potassium permanganate. Give the equation for the reaction in the column. 5.26. Pure hydroiodic acid (HI) cannot be prepared by adding concentrated sulfuric acid to sodium iodide and distilling off the hydroiodic acid, because of side reactions. One side reaction yields hydrogen sulfide, as noted by the odor. Give the equation for this side reaction. 5.27. Write the balanced equation for the reaction that occur when chlorine gas is bubbled through a solution of iron(II) bromide. 5.28. In the final step of producing bromine from sea water, a mixture of sodium bromide and sodium bromate is treated with sulfuric acid. Give the equation for the reaction; balance it. 5.29. A microchemical procedure uses a cadmium amalgam (cadmium dissolved in metallic mercury) to reduce iron salts to their lowest oxidation state prior to titration with standard solution. Give the equation for the reaction involving the cadmium. 5.30. When zinc is heated with concentrated sulfuric acid, hydrogen sulfide is evolved. Write the chemical reaction; balance it. 5.31. The Marsh test for the detection of arsenic depends on the reaction of an arsenic compound, such as H3AsO4, with metallic zinc in acid solution. The arsenic is liberated as arsine, AsH3, which may be decomposed by heat to give an "arsenic mirror". Write the balanced equation for the reaction that occurs in the case of the arsenic-positive test. 24 6. CALCULATIONS BASED ON CHEMICAL EQUATIONS 6.1. When mercury oxide, HgO, is heated, it releases mercury and oxygen gas. How many moles of oxygen gas will be produced from the decomposition of 4 mol of mercury oxide? 6.2. How many molecules of potassium chlorate are required in the preparation of 6 mol of oxygen gas? 6.3. When aluminum is heated with sulfur, aluminum sulfide is formed. a) Write the balanced equation. b) Calculate the number of moles of aluminum that combines with 6 mol of sulfur. c) Calculate the number of aluminum sulfide molecules produced from 0.4 mol of Al. 6.4. If 212 grams of sodium carbonate react with calcium hydroxide, how many grams of sodium hydroxide are formed? 6.5. How many grams of sodium hydroxide will react with 49 g of phosphoric acid? 6.6. How many liters of oxygen (at STP) are liberated by heating 490 g of potassium chlorate? 6.7. Consider the reaction MnO2 + 4 HCl → MnCl2 + Cl2 + 2 H2O. How many grams of MnO2 are required to produce 5.6 L of Cl2 at STP? 6.8. If 152 mL of liquid carbon disulfide (density 1.25 g/mL) are burned completely: a) how many liters of SO2 at STP are formed? b) how many liters of O2 are required at STP? 6.9. How many liters of carbon dioxide are formed from the combustion of 60 liters of ethylene gas, C2H4? Recall that the combustion of any compound made from C and H elements produces carbon dioxide and water vapor. 6.10. Given the balanced equation N2 + 3 H2 = 2 NH3, calculate (assuming that all volume measurements are made under identical conditions): a) the volume of H2 that reacts with 12 L of N2; b) the volume of N2 that reacts with 12 L of H2; c) the volume of NH3 produced from 4 L of N2; d) the volumes of N2 and H2 to produce 60 L of NH3; 25 6.11. Aluminum reacts with hydrochloric acid and produces aluminum chloride and hydrogen gas. Answer the following questions for 2.7 g of aluminum used in the reaction. a) How many grams of AlCl3 will be produced? b) How many moles of HCl are used? c) How many molecules of H2 are formed? 6.12. The combustion of ammonia, NH3, produces NO and H2O. a) Write the balanced equation representing the reaction. b) How many moles of H2O are produced when 2 mol of NH3 is burned? c) How many moles of O2 are required to react completely with 3 mol of NH3? d) How many grams of NO are produced when 16 grams of O2 are used? e) How many grams of H2O are formed when 8.96 L of NH3 at STP is completely burned? f) How many liters of NO at STP will be produced when 1.8x2023 NH3 molecules are burned? g) How many liters of O2 and how many liters of air are required to burn 20 L of NH3? (Assume the identical conditions. Recall that 1/5 of air is O2 by volume.) 6.13. A portable hydrogen generator utilizes the reaction: CaH2 + 2 H2O → Ca(OH)2 + 2 H2↑. How many grams of H2 can be produced by 50 g of CaH2? 6.14. How much iron(III) oxide can be produced from 6.76 g of FeCl3·6H2O by the following reactions? FeCl3·6H2O + 3 NH3 = Fe(OH)3 + 3 NH4Cl + 3 H2O; 2 Fe(OH)3 = Fe2O3 + 3 H2O. 6.15. In a rocket motor fueled with butane, C4H10, how many kilograms of liquid oxygen should be provided with each kilogram of butane to provide for complete combustion? 6.16. Ethyl alcohol, C2H5OH, can be made by the fermentation of glucose, C6H12O6, as indicated by the (unbalanced) equation: C6H12O6 → C2H5OH + CO2. How many metric tons of alcohol can be made from 2.00 metric tons of glucose? 6.17. In the Mond process for purifying nickel, the volatile nickel carbonyl, Ni(CO)4, is produced by the reaction: Ni + 4 CO = Ni(CO)4. How much CO is used in volatilizing each kilogram of nickel? 26 6.18. The mixture of 2 mol of H2 and 2 mol of O2 gases are ignited to obtain water. Which reactant is limiting? Which is the excess reactant? How much water will be produced? 6.19. A mixture of 100 g Al and 200 g MnO was heated to initiate the reaction: 2 Al + 3 MnO = Al2O3 + 3 Mn. Which initial substance remained in excess? How much? 6.20. Carborundum, SiC, is used as an abrasive. It is formed by the combination of SiO2 and carbon, according to the reaction: SiO2 + 3 C = SiC + 2 CO. What mass of SiC is formed from 6 grams of SiO2 and 6 grams of C? 6.21. How many grams of water are produced when 4 g of H2 and 8 g of O2 are reacted? 6.22. Given: N2 + 3 H2 = 2 NH3. If 20 L of N2 and 15 L of H2 gases at the same conditions are reacted, which gas will be excess and how many liters? 6.23. Given: N2 + 3 H2 = 2 NH3. 3.01x1023 molecules of nitrogen and 3.36 L of H2 at STP are reacted. How many grams of NH3 are produced? 6.24. Aluminum and hydrogen bromide react according to the following reaction: 2 Al + 6 HBr = 2 AlBr3 + 3 H2. If 4 mol of Al and 9 mol of HBr are allowed to react, a) which of the two reactants is the limiting one? b) how many moles of the excess reactant are left at the end of reaction? c) what is the maximum mole number of H2 obtained? 6.25. 18 g of C and 8 g of oxygen are reacted to form CO2. Which element and how many grams remain behind? 6.26. Given: the reaction 2 H2S + 3 O2 = 2 H2O + 2 SO2. The quantities of reactants are given below. For each of the following, determine the excess reactant and the maximum grams of water produced. a) 2 mol of H2S and 4 mol of O2; b) 4 mol of H2S and 6 mol of O2; c) 8.5 g of H2S and 9.6 g of O2; d) 6.02x1022 H2S molecules and 6.72 L O2 at STP; e) 4.48 L H2S at STP and 19.2 g O2; f) 17.92 L H2S at STP and 13.44 L O2 at STP. 6.27. Given the reaction: As4O6 + 4 I2 + 4 H2O = 2 As2O5 + 8 HI. What is the maximum grams of HI produced if 2 mol of each of the reactants are reacted? 27 6.28. Nitric oxide, NO, is prepared according to the following reaction in laboratories: 3 KNO2 + KNO3 + Cr2O3 = 4 NO + 2 K2CrO4. Calculate the maximum liters of NO at STP produced by the reaction of 100 g of each of the reactants. 6.29. Equal weights of sodium and chlorine gas are reacted in a closed container to give 0.1 mol of sodium chloride. Which element will remain behind and how many grams? 6.30. Equal moles of aluminum and oxygen are reacted to give 20.4 g of aluminum oxide. Which one remains unreacted and how many moles? 6.31. Equal volumes of sulfur dioxide and oxygen gases are reacted to give 5 liters of sulfur trioxide at the same conditions. Which one remains unreacted and how many liters? 6.32. A mixture of 1 ton of CS2 and 2 tons of Cl2 is passed through a hot reaction tube, where the following reaction takes place: CS2 + 3 Cl2 → CCl4 + S2Cl2. a) How much CCl4 can be made by complete reaction of the limiting starting material? b) Which starting material is in excess, and how much of it remains unreacted? 6.33. What mass of Cu2S can be produced from the reaction of 100 g copper with 50 g of sulfur? 6.34. What weight of HCl is produced when sulfuric acid reacts with 200 grams of 87.75% pure sodium chloride (assume that 12.25% of the sample is inert in the reaction)? 6.35. How many liters (at STP) of oxygen can be liberated from 1700 grams of a solution which is 3.0% hydrogen peroxide by mass? The equation is: 2 H2O2 → 2 H2O + O2↑. 6.36. How many grams of H2SO4 can be produced from 300 g of FeS2 which is 60 % pure by weight? 6.37. How many grams of sodium chloride that is 90 % pure are required to produce 73 g of HCl according to the reaction with H2SO4? 6.38. A 25 g sample of iron reacts with 200 g of 14.6 % HCl solution by mass. The reaction is: Fe + 2 HCl = FeCl2 + H2. Calculate the percentage of iron in the sample. (Assume the impurities are inert to HCl.) 28 6.39. When an unknown quantity of magnesium is reacted with HCl, 4.48 L of H2 at STP together with some magnesium chloride are formed. a) What mass of magnesium chloride is formed? b) If the sample of magnesium is 96 % pure, what mass of magnesium sample is used in the reaction? c) What mass of HCl solution that is 20 % HCl by mass would it be required to produce 4.48 L of H2 at STP? 6.40. When 20 g of iron is reacted with oxygen, 20 g of iron(III) oxide is formed. What percentage of iron is reacted with oxygen? 6.41. The acetylene gas, C2H2, is an important raw material in the production of many chemicals, such as synthetic rubber, alcohol, etc. It may be prepared from limestone (CaCO3), coke (C) and water according to the following reactions: I. CaCO3 → CaO + CO2; II. CaO + 3 C → CaC2 + CO; III. CaC2 + H2O → C2H2 + Ca(OH)2. Assuming an excess of all other reactants, how many liters of C2H2 at STP can be obtained from 50 g CaCO3. 6.42. KBrO4 may be prepared by the following series of reactions: I. Br2 + 2 KOH → KBr + KBrO + H2O; II. 3 KBrO → 2 KBr + KBrO3; III. 4 KBrO3 → 3 KBrO4 + KBr. Assuming the excess KOH, how much Br2 in grams is needed to prepare 109.8 g KBrO4 by the above sequence of reactions? 6.43. Given the reactions: I. Al4C3 + 12 H2O = 4 Al(OH)3 + 3 CH4; II. CH4 + 2 O2 = CO2 + 2 H2O. The methane gas that is obtained from 50 g impure sample of Al4C3 is required 38.4 g of O2 to be completely burned. What is the percentage purity of Al4C3 in the impure sample? 6.44. Iron is prepared in the blast furnace according to the sequence of these reactions: I. 2 C + O2 = 2 CO; II. 3 CO + Fe2O3 = 2 Fe + 3 CO2. Assuming the excess of O2, how many tons of iron can be obtained by the reaction of 5 tons of hematite or Fe2O3, that is 80 % pure, with 1 ton of coke? 6.45. To burn 30 liters of a mixture of C3H4 and C3H8 gases at STP, 140 liters of O2 are needed at the same conditions. Calculate the volume of C3H4 in the mixture. 29 6.46. The complete combustion of a 13.44 L mixture of C2H4 and C3H4 gases at STP produces 31.36 L CO2 under the same conditions. Find the mole number of each gas in the mixture. 6.47. 11.9 g of an alloy made from Al and Zn is reacted with sufficient amount of HCl and 8.96 L of H2 at STP are produced. What is the amount of Al in the alloy? 6.48. A 20 g alloy of Mg and Al elements is reacted with HCl and 24.64 L of H2 at STP are produced. Find the percentage by mass of Al in the mixture. Both metals react with HCl and produce metal chlorides and hydrogen gas. 6.49. Both sodium and calcium metals react with water to produce metal hydroxides and H2 gas. If 4 moles of H2 are obtained from 5 moles of the mixture of sodium and calcium metals, calculate the mole percentage of sodium in the mixture. 6.50. When 2.2 g of a compound containing carbon and hydrogen is burned, 3.36 liters of CO2 at STP are produced. What is the empirical formula of the compound? 6.51. The complete combustion of 8 g of compound made from only C and H produced 26.4 g CO2. What is the empirical formula of the compound? 6.52. When 2.3 g of a compound containing C, H and O is burned completely, 4.4 g of CO2 and 2.7 g of H2O are produced. Find its empirical formula. 6.53. When 1.76 g of a compound containing C, H and O is burned completely in oxygen, 3.52 g of CO2 and 1.44 g of H2O are produced. a) Calculate the empirical formula of the compound. b) If 0.05 mol of the compound is 4.4 g, what is the molecular formula of the compound? 6.54. Copper(II) nitrate is prepared by dissolving a weighed amount of copper metal in a nitric acid solution: 3 Cu + 8 HNO3 → 3 Cu(NO3)2 + 2 NO↑ + 4 H2O. What volume of 6.00 M HNO3 should be used to prepare 10.0 g of Cu(NO3)2? 6.55. The preparative task is to precipitate all the Ag+ from 50 mL of 0.12 M AgNO3 solution. Answer the following questions. a) What weight of AgCl can be obtainedl? b) What weight of NaCl is required to precipitate the AgCl? c) What volume of 0.24 M HCl would be needed for the task? 6.56. How many milligrams of Na2CO3 will react with 45.00 mL of 0.2500 M HCl? 30 6.57. What weight of silver and what volume of 6.00 M HNO3 are needed for the preparation of 500 mL of 3.00 M AgNO3? 6.58. How many tons of limestone (CaCO3) are needed to prepare 5.00 tons of dry ice (CO2), assuming that 30% of the CO2 produced is wasted in converting it to the solid? 6.59. What volume of commercial HCl (36% HCl by mass, density = 1.18 g/mL) and what weight of limestone (90% pure) are needed to produce 2.00 kg of CO2? 6.60. What volume of commercial HCl (36% HCl by mass, density = 1.18 g/mL) and what weight of pyrolusite (85% MnO2) are needed to produce 5.00 kg of Cl2? 6.61. How many grams of 95% pure NaCl are needed to produce 2.00 kg of HCl? 6.62. Commercial sulfuric acid that has a density of 1.84 g/mL and is 95% H2SO4 by mass is used for the production of 365 g of HCl. What mass and volume of commercial acid is needed? 6.63. A manufacturer supplies 1 kg cans of calcium carbide whose purity is labeled as 85%. What volume of acetylene can be prepared from 1 kg of this product if the label is correct? 6.64. How many grams of sand, SiO2, are needed to prepare 1 kg of SiF4, assuming that 25% of the sand is inert material and does not produce SiF4? What volume of SiF4 is obtained, measured at STP? REFERENCES 1. Dictionary of Chemistry. – McGraw-Hill Inc., 2003. – 443 p. 2. Hoenig, Steven L. Basic Training in Chemistry. – Kluwer Academic Publishers, 2002. – 184 p. 3. Rosenberg, Jerome L., Epstein, Lawrence M. College Chemistry. – McGraw-Hill Companies, Inc., 2000. – 154 p. 4. Rosenberg, Jerome L., Epstein, Lawrence M. Theory and Problems of College Chemistry. – McGraw-Hill Companies, Inc., 1997. – 386 p. 5. Smith, Robert Nelson, Pierce, Conway. Solving General Chemistry Problems. – W.H.Freeman & Company., 1980. – 474 p. 6. Williams, Linda. Chemistry Demystified. – McGraw-Hill Companies, Inc., 2003. – 280 p. 31 PERIODIC TABLE I II III IV V H 1 2 3 4 5 6 7 Hydrogen 1 1.0079 Li Lithium 3 6.94 Na Sodium 11 22.99 K Potassium 19 39.098 Cu Copper 29 63.54 Rb Rubidium 37 85.47 Ag Silver 47 107.87 Cs Cesium 55 132.905 Au Gold 79 196.97 Fr Francium 87 [223] Lanthanides Gd 64 Gadolinium 157.2 Actinides Cm 96 Curium [247] B Be Beryllium 4 9.012 Mg Magnesium 12 24.305 Ca Calcium 20 40.08 Zn Zinc 30 65.38 Sr Strontium 38 87.62 Cd Cadmium 48 112.41 Ba Barium 56 137.33 Hg Mercury 80 200.5 Ra Radium 88 226.03 La 57 Tb 65 Ac 89 Bk 97 C N Nitrogen Carbon 14.0067 6 12.011 7 P Si Phosphorus Silicon 30.974 14 28.085 15 Ti V Titanium Vanadium 22 47.90 23 50.94 As Ge Arsenic Germanium 74.92 32 72.59 33 Zr Nb Zirconium Niobium 40 91.22 41 92.906 Sn Sb Tin Antimony 50 118.69 51 121.75 Hf Ta Hafnium Tantalum La–Lu 72 178.49 73 180.95 Bi Pb Tl Bismuth Lead Thallium 208.98 207.2 83 81 204.3 82 Rf Db Rutherfordium Dubnium Ac–(Lr) 104 [261] 105 [262] Boron 5 10.81 Al Aluminum 13 26.98 Sc Scandium 21 44.956 Ga Gallium 31 69.72 Y Yttrium 39 88.91 In Indium 49 114.82 Lanthanum 138.905 Terbium 158.93 Actinium [227] Berkelium [247] Ce 58 Dy 66 Th 90 Cf 98 32 Cerium 140.12 Dysprosium 162.50 Thorium 232.038 Californium [251] Pr Praseodymium 59 140.9077 Ho Holmium 67 164.93 Pa Protactinium 91 231.036 Es Einsteinium 99 [254] OF CHEMICAL ELEMENTS VI Appendix 1 VII VIII (H) O F Fluorine Oxygen 18.998 8 15.999 9 Cl S Chlorine Sulfur 35.453 16 32.06 17 Cr Mn Chromium Manganese 24 51.996 25 54.938 Br Se Bromine Selenium 79.904 34 78.96 35 Mo Tc Molybdenum Technetium 42 95.94 43 98.906 Te I Tellurium Iodine 52 127.6 53 126.90 W Re Tungsten Rhenium 74 183.8 75 186.21 At Po Astatine Polonium [210] 84 [209] 85 Sg Bh Seaborgium Bohrium 106 [266] 107 [264] Nd 60 Er 68 U 92 Fm 100 He Fe 26 Iron 55.847 Ru Ruthenium 44 101.07 Os Osmium 76 190.2 Hs Hassium 108 [277] Neodymium Pm Promethium 144.24 61 [145] Erbium Tm Thulium 167.26 69 168.93 Uranium Np Neptunium 238.029 93 237.048 Fermium Md Mendelevium [257] 101 [258] 33 Sm 62 Yb 70 Pu 94 No 102 Helium 2 4.0026 Ne Neon 10 20.179 Ar Argon 18 39.948 Co Ni Cobalt Nickel 27 58.933 28 58.70 Kr Krypton 36 83.80 Rh Pd Rhodium Palladium 45 102.9 46 106.4 Xe Xenon 54 131.3 Ir Pt Iridium Platinum 77 199.2 78 195.1 Rn Radon 86 [222] Mt Meitnerium 109 [268] Samarium 150.4 Ytterbium 173.04 Plutonium [244] Nobelium [255] Eu 63 Lu 71 Am 95 Lr 103 Europium 151.96 Lutetium 174.967 Americium [243] Lawrencium [256] Appendix 2 Elements and Electronegative Components Symbol Ac Al Ag Am Ar As At Au B Ba Be Bh Bi Bk Br C Ca Cd Ce Cf Cl Cm Co Cr Cs Cu Db Dy Er Es Eu F Fe Fm Fr Name Transcription actinium aluminum silver americium argon arsenic astatine gold boron barium beryllium bohrium bismuth berkelium bromine carbon calcium cadmium cerium californium chlorine curium cobalt chromium cesium copper dubnium dysprosium erbium einsteinium europium fluorine iron fermium francium αk_'tin_i: _əm ə_'lu:m_ə_nəm 'sil_vər αm_ə_'ris_i: _əm 'a:r_gən 'a:rs_ən_ik 'αs_tə_ti:n gould 'bo:_rən 'bαr_i:_əm bə_'ril_i: _əm 'bo:r_i: _əm 'biz_məθ 'bə:r_kli: _əm 'brou_mi:n 'ka:r_bən 'kαl_si:_əm 'kαd_mi:_əm 'sir_i:_əm kalə_'fo:r_ni:_əm 'klo:r_i:n 'kju:r_i:_əm 'kou_bo:lt 'krou_mi:_əm 'si:_zi:_əm 'kop_ər 'du:b_ni:_əm dis_'prou_zi:_əm 'ə:r_bi:_əm aın_'staın_i:_əm yu:_'rou_pi:_əm 'flu:r_i:n 'aı_ərn 'fer_mi:_əm 'frαn_si:_əm 34 Electronegative component Transcription arsenide 'a:rs_ən_aıd boride 'bo:r_aıd beryllide bə_'ril_aid bromide carbide 'brou_maıd 'ka:r_baıd chloride 'klo:r_aıd fluoride 'flu:r_aıd Appendix 2 (continued) Symbol Ga Gd Ge H He Hf Hg Ho Hs I In Ir K Kr La Li Lr Lu Md Mg Mn Mo Mt N Na Nb Nd Ne Ni No Np O Os P Pa Pb Pd Name gallium gadolinium germanium hydrogen helium hafnium mercury holmium hassium iodine indium iridium potassium krypton lanthanum lithium lawrencium lutetium mendelevium magnesium manganese molybdenum meitnerium nitrogen sodium niobium neodymium neon nickel nobelium neptunium oxygen osmium phosphorus protactinium lead palladium Transcription 'gαl_i:_əm gαd_əl_'in_i:_əm jə:r_'meın_i:_əm 'haı_drə_jən 'hi:_li:_əm 'hαf_ni:_əm 'mə:r_kyə_ri: 'houl_mi:_əm 'ha:_si:_əm 'aı_ə_daın 'in_di:_əm i_'rid_i:_əm pə_'tαs_i:_əm 'krip_tən 'lαn_θə_nəm 'liθ_i:_əm 'lou_'ren_si:_əm lu:_ti: _shəm 'men_də_li:_vi:_əm mαg_'ni:_zi:_əm 'mαŋ_gə_ni:s mə_'lib_de_nəm maıt_'nir_i:_əm 'naı_trə_jən 'soud_i:_əm naı_'ou_bi:_əm ni:_ou_'dim_i:_əm 'ni:_on 'nik_əl nou_'bel_i:_əm nep_'tu:_ni:_əm 'ok_sə_jən 'oz_mi:_əm 'fos_fə_rəs prout_αk_'tin_i:_əm led pə_'leıd_i:_əm 35 Electronegative component Transcription germanide hydride 'jə:r_mə_naıd 'haı_draıd iodide 'aı_ə_daıd nitride 'naı_traıd oxide 'ok_saıd phosphide 'fo_sfaıd plumbide 'pləm_baıd Appendix 2 (end) Symbol Name Transcription Po Pm Pr Pt Pu Ra Rb Re Rf Rh Rn Ru S Sb Sc Se Sg Si Sm Sn Sr Ta Tb Tc Te Th Ti Tl Tm U V W Xe Y Yb Zn Zr polonium promethium praseodymium platinum plutonium radium rubidium rhenium rutherfordium rhodium radon ruthenium sulfur antimony scandium selenium seaborgium silicon samarium tin strontium tantalum terbium technetium tellurium thorium titanium thallium thulium uranium vanadium tungsten xenon yttrium ytterbium zinc zirconium pə_'lou_ni:_əm prə_'mi:_thi:_əm preı_zi:_ou_'dim_i:_əm 'plαt_ən_əm plu:_'tou_ni:_əm 'reı_d_i:_əm ru:_ 'bid_i:_əm 'ri:_ni:_əm rəð_ər_'fo:r_di:_əm 'roud_i:_əm 'reı_dən ru:_ 'thi:_ni:_əm 'səl_fər 'αn_tə_'mou_ni: 'skαn_di:_əm sə_'li:_ni:_əm si:_ 'bo:rg_i:_əm 'sil_ə_kən sə_'mαr_i:_əm tin 'stron_ti:_əm 'tαnt_əl_əm 'tə:r_bi:_əm tek_'ni:_shi:_əm tə_'lu_ri:_əm 'tho:r_i:_əm taı_'teı_ni:_əm 'θαl_i:_əm 'θu:_li:_əm yə_'reı_ni:_əm və_'neıd_i:_əm 'təŋ_stən 'zi:_non 'i_tri:_əm i_'tə:r_bi:_əm ziŋk zə:r_'kou_ni:_əm 36 Electronegative component Transcription sulfide 'səl_faıd selenide 'sel_ə_naıd silicide 'sil_ə_saıd telluride tə_'lu_raıd Appendix 3 Acids and Anions Formula Acid HCl HClO HClO2 HClO3 HClO4 hydrochloric hypochlorous chlorous chloric perchloric Transcription haı_drə_'klo:r_ik haı_pə_'klo:r_əs 'klo:r_əs 'klo:r_ik pə:r_'klo:r_ik Anion chloride hypochlorite chlorite chlorate perchlorate Transcription 'klo:r_aıd haı_pə_'klo:r_aıt 'klo:r_aıt 'klo:r_eıt pə:r_'klo:r_eıt (similar with other halogens) HCN HMnO4 HNO2 HNO3 HOCN HSCN CH3COOH H2C2O4 H2CO3 H2Cr2O7 H2CrO4 H2S H2SiO3 H2S2O3 H2SO3 H2SO4 H3AsO3 H3AsO4 H3BO3 H3PO3 H3PO4 hydrocyanic permanganic nitrous nitric cyanic thiocyanic acetic oxalic carbonic dichromic chromic hydrosulfuric silicic thiosulfuric sulfurous sulfuric arsenious arsenic boric phosphorous phosphoric haı_drou_saı_'an_ik pə:r_mαn_'gαn_ik 'naı_trəs 'naı_trik saı_'αn_ik θaı_ou_saı_'αn_ik ə_'si:t_ik ok_'sαl_ik ka:r_'bon_ik daı_'krou_mik 'krou_mik haı_drə_səl_'fyur_ik sə_'lis_ik θaı_ə_səl_'fyur_ik 'səl_fə_rəs 'səl'fyur_ik a:r_'si:n_i:_əs a:r_'sen_ik 'bo:r_ik 'fos_fə_rəs fos_'fo:r_ik 37 cyanide permanganate nitrite nitrate cyanate thiocyanate acetate oxalate carbonate dichromate chromate sulfide silicate thiosulfate sulfite sulfate arsenite arsenate borate phosphite phosphate 'saı_ə_naıd pə:r_'mαŋ_gə_neıt 'naı_traıt 'naı_treıt 'saı_ə_neıt θaı_ou_'saı_ə_neıt 'αs_ə_teıt 'ok_sə_leıt 'ka:r_bə_nət daı_'krou_meıt 'krou_meıt 'səl_faıd 'sil_ə_kət θaı_ə_'səl_feıt 'səl_faıt 'səl_feıt 'a:r_sə_naıt 'a:rs_ən_eıt 'bo: _reıt 'fos_faıt 'fos_'feıt ХИМИЯ НА АНГЛИЙСКОМ ЯЗЫКЕ Модуль 1 БАЗОВЫЕ ХИМИЧЕСКИЕ ПОНЯТИЯ Учебное пособие 38