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CHEMISTRY SOCIETYYCHETRY SOCISIETMCouncil of Student Organization76DELASARSITY19LLE UNIVDe La Salle UniversityEInorganic Chemistry 1Comprehensive ReviewerAnswer each of the following questions. For each questions requiring numerical answer, showall the calculations then draw a box around the final answer. Observe the use of significantfigures. Use the given atomic masses below to solve the problems.H 1.008Br 79.90Ne 20.18C 3.00 x 108 m/sCNS12.0114.0132.07OAlI16.0026.98126.9h 6.626 x 10-34 J-s/photonClBaF35.45137.319.00RH 2.179 x 10-18 J1. Give the number of significant figures in:a. 2.0 x 10-3b. 0.06022c. 0.2500d. 3.242. Indicate whether the sample is a pure substance or a mixture. If it is a substance, indicatedwhether it is a compound or an element. If it is a mixture, indicate whether it ishomogeneous or heterogeneous.a. fresh airb. icec. sugar and sand3. Which of the following are chemical changes?a. milk souringb. silver tarnishingc. butter meltingd. coal burning4. Which process/es in # 3 is/are physical chemical changes?5. Which of the following is/are exact numbers?a. There are 12 eggs in a dozenb. The boiling point of methylene chloride is measured to be 42 C.c. Neil Armstrong was on the moon for 2 hours, 31 minutes.d. There are 73 million people in the Philippines.
6. Which of the following is/are physical changes?a. combustibilityb. brittlenessc. heat conductivityd. color7. The following data refer to the element iodine (atomic number 53).following would be physical property/properties?a. its density is 4.93 g/cm3 at 20oC and 1 atmb. iodine has a purple colorc. it reacts with chlorined. its normal melting point is 113.5oCWhich of the8. Given the following substances: SO2, S8, Cs, N2, N2O5, COa. Which is/are element/s?b. Which is/are compound/s?c. Which is/are not molecule/s?9. Write the nuclear symbol for each of the following:a. The chlorine atom with 17 protons and 18 neutrons, 18 electronsb. The bromine atom with atomic number 35 and mass number 7910. Fill in the blanks of the following table54SymbolFe 2 26no. of protonsno. of neutronsno. of electronsnet charge5651618-311. The hormone thyroxine secreted by the thyroid gland has the formula C15H11NO4I4.a. How many elements are present in the molecule?b. How many atoms are present in one molecule of thyroxine?c. How many molecules are present in one mole of thyroxine?d. How many atoms are present in one mole of thyroxine?12. Methyl salicylate is a common active ingredient in liniments such as Ben-Gay. It is alsoknown as oil of wintergreen. It is made up of carbon, hydrogen and oxygen atoms. When asample of methyl salicylate weighing 5.287g is burned in excess oxygen, 12.24g of carbondioxide and 2.505g of water are formed. What is the simplest formula for oil of wintergreen?For questions 13-18: Aspartame is an artificial sweetener that is 160 times sweeter than sucrose(table sugar) when dissolved in water. It is marketed as Nutra-Sweet. The molecular formula ofaspartame is C14H18N2O5.
13. Calculate the molar mass of aspartame.14. How many moles of aspartame are present in 10.0 g of aspartame?15. Calculate the mass in grams of 1.56 moles of aspartame.16. How many atoms of nitrogen are there in 1.20 g of aspartame?17. What is the mass in grams of 1.00 x 109 molecules of aspartame?18. Calculate the percent composition of aspartame.For questions 19-20: A compound contains 47.08% carbon, 6.59% hydrogen and 46.3%chlorine by mass. The molar mass of the compound is 153 g/mole.19. What is the empirical formula of the compound?20. What is the molecular formula of the compound?21. How would you describe the nuclear model of an atom to a non-science major?22. Briefly define pressure and give 2 common units for it.23. Why is mercury a more suitable substance to use in a barometer than water?24. State the following gas laws in words and also in equation form. In each case, indicate theconditions under which the law is applicable (that is, what should be kept constant).a. Boyle’s Lawb. Charles’ Lawc. Avogadro’s Lawd. Dalton’s Law25. Why does a weather balloon expand as it rises in the air? Assume that the temperatureremains constant.26. What are the values of the standard temperature and pressure?27. A sample of O2 gas occupies a volume of 5.75 liters at 0.890 atm. If the temperature and thenumber of moles are kept constant, calculate the volume when the pressure is:a. increased to 1.25 atmb. decreased to 0.350 atm28. The atmosphere of Venus is mostly carbon dioxide. At the surface of Venus, the temperatureis about 800 C and the pressure is about 75 atm. What volume would one mole of an idealgas occupy in Venus?29. A NASA scientist proposed that barium peroxide, BaO2 (s), be used on a space capsule inorder to supply emergency oxygen. It decomposes on heating according to the equation:2 BaO2 (s) 2 BaO (s) O2 (g)What mass of BaO2 (s) would be needed to supply enough oxygen to fill up a 1.00 x 104 literspace capsule to a pressure of 0.20 atm at 25 C?
30. Nitrogen trifluoride gas reacts with water to form the gases NO, HF and NO2.a. Write a balanced equation for the reaction.b. What volume of NO is formed when 6.00 liters of nitrogen trifluoride are made to reactwith 6.00 liters of water? Assume 100% yield and constant temperature and pressurethroughout the reaction.31. If an aerosol can contains a gas at 1.82 atm pressure at 22 C, what will be the gas pressure inthe can if it is dumped into an incinerator at 935 C? (Hint: the aerosol can is rigid and cannotincrease in volume.)32. A 12.8-liter cylinder contains 35.8 grams of O2 at 46.0 C. What is the pressure of this gas inatmospheres?33. Methyl isocyanate is a volatile, highly toxic gas that killed thousands of people in Bhopal,India in 1984. It is made up of 42.1% C, 5.30% H, 24.6% N and oxygen.a. What is the empirical formula of methyl isocyanate?b. A sample of the volatile liquid is vaporized completely in a 0.125-liter flask at 99 C and745 mmHg. The vapor is condensed and it weighed 0.229g. What is the molar mass ofmethyl isocyanate?c. What is the molecular formula of methyl isocyanate?34. What is the density of iodine chloride (ICI) gas at 127 C and 763 mmHg?35. A gaseous mixture contains 5.78 g of CH4, 2.15 g of Ne and 6.80 g of SO2. What pressure isexerted by the mixture inside a 75.0-liter cylinder at 85 C? Which gas contributes thegreatest pressure?36. Which gas would effuse faster in a glass tubing HI or HCl? What is the ratio of their rates ofeffusion?37. Discuss the following briefly.a. Differentiate between an exothermic and an endothermic reaction.b. What is the sigh of ΔH for an exothermic reaction?c. State the law of conservation of energy.d. When solid sodium nitrate is dissolved in water, the solution becomes cool to touch. Isthis process an en exothermic or an endothermic change?For questions 38-39: An infrared ray frequency of 5.71 x 1012 s-1.38. Calculate the wavelength.39. Calculate the energy in joules per photon.For questions 40-41: A beam of x-rays has a wavelength of 8.00 x 10-9 m.40. What is the energy of x-rays?
41. The ionization energy of potassium is 419 kJ/mole; that is, the minimum energy required toremove the outermost electron from potassium. Will the x-rays of 8.00 x 10-9 m wavelengthbe sufficient to ionize potassium? Why or who not?For questions 42-45: Consider the following transitions in the hydrogen atom:I.n 1 to n 3II.n 3 to n 4III.n 3 to n 2IV.n 5 to n 342. Which involves the ground state?a. I onlyb. I and II onlyc. III onlyd. IV onlye. II only43. Which absorbs the most energy?a. I onlyb. II onlyc. III onlyd. IV only44. Which emits the most energy?a. I onlyb. II onlyc. III onlyd. IV only45. What are the possible values of ml for l 2?46. Which of the following orbitals will have the highest energy in a many-electron atom?a. 3sb. 5fc. 3pd. 1se. 4d47. How many subshells are found in n 3 level?48. What is the total number of orbitals in the n 3 level?49. How many orbitals have the values n 4 and l 3?50. What is the total capacity for electrons on the n 4 level?
51. How many unpaired electrons are there in phosphorous (Z 15)?52. How many 3d electrons are there in bromine (Z 35)?53. How many electrons are there in bromine with quantum number l 1?54. How many outer electrons are there in magnesium (Z 12)?55. Give the possible set of quantum numbers (n, l, ml, ms) for the outermost electron of sodium(Z 11)?56. What is the energy involved for a transition of an electron form n 5 to n 4 in a Bohrhydrogen atom?57. If traveling at equal speeds, which of the following matter waves have the longestwavelength?a. electronb. photonc. neutrond. a baseball58. All halogens (Group VIIA) have seven electrons in their outermost shells. Are halogensparamagnetic or diamagnetic? How many unpaired electrons do they have?59. Which of the four quantum numbers determine the shape of the orbital?60. Which of the four quantum numbers determine the orientation of the orbital in space?61. Which orbital does not exist?a. 1pb. 2sc. 3dd. 4fe. 3p62. Which atomic orbital has an electron density distribution in the shape of a sphere?
Answer Key1. a. 2c. 4b. 4d. 32. a. mixture, homogenousb. substance, compoundc. mixture, heterogeneous3. a, b and d4. c5. a6. b, c and d7. a, b and d8. a. S8, N2 and Csb. SO2, N2O5 and COc. Cs9. a. 35 Cl 17b.79Br3510.Symbolno. of protonsno. of neutronsno. of electronsnet charge11B54Fe 2 31P 3-526155650262824 2151618-311. a. 5b. 15 C 11 H 1N 4O 4I 35 atoms6.022 x 1023 moleculesc. 1.00 mol x 6.022 x 1023 molecules1 mol6.022 x 1023 molecules35 atoms25d. 1.00 mol xx1 mol1 molecule 2.11 x 10 atoms12. CxHyO2 O2 CO2 H2OCxHyO2 5.287 gCO2 12.24 gH2O 2.505 g1 mol CO21 mol C12.24 g CO2 x 44.01 g CO x 1 mol CO2212.01 g C 0.2781 mol C x 1 mol C 3.340 g C
1 mol H2O2 mol H2.505 g H2O x 18.0126 g H O x 1 mol H O221.008 g H 0.2781 mol H x 1 mol H 0.2803 g H5.287 g – (3.340g C 0.2803 g H)1 mol O 1.667 g O x 16.00 g O 0.1042 mol O C0.2781 H2.67 O C 8/3 H 8/3 O C8H8O313. C14H18N2O514 C x 12.01 168.14 g18 H x 1.01 18.18 g2 N x 14.01 28.02 g5 O x 16.00 80.00 g 294.34 g C14H18N2O51 mol14. 10.0 g C14H18N2O5 x 294.34 g 3.40 x 10-2 mol C14H18N2O5294.34 g15. 1.56 mol C14H18N2O5 x 1 mol 459 g C14H18N2O51 mol6.022 x 10 23 molecules2 atoms N216. 1.20 g C14H18N2O5 x 294.34 g xx 1 moluecule1 mol 4.91 x 10 21 atoms of N21 mol294.34 g17. 1.00 x 109 molecules C14H18N2O5 x 6.022 x 10 23 molecules x 1 mol 4.89 x 10-13 g C14H18N2O518. C14H18N2O5168.14 gC 294.34 g 0.5712 57.12%18.18 gH 294.34 g 0.0618 6.18%28.02 gN 294.34 g 0.0952 9.52%80.00 gO 294.34 g 0.2718 27.18%19. Basis 100 gMassC 47.08 %47.08 gH 6.59 %6.59 gCl 46.33 %46.33 g1 molC 47.08 g x 12.02 g 3.920 moles3.920 1.307 2.999 3
1 molH 6.59 g x 1.008 g 6.54 moles6.54 1.307 5.003 51 molCl 46.33 g x 35.45 g 1.307 moles1.307 1.307 1Empirical formula: C3H5Cl20. C3 3(12.01) 36.03 gH5 5(1.008) 5.04 gCl 1(35.45) 35.45 g 76.52 g C3H5Cl15376.52 1.99 2Molecular formula: C6H10Cl221. Be imaginative ( Answer in your own words).22. a. pressure – force applied per unit areaFP Ab. atm, mmHg, Torr23. Mercury has greater density than water. If water were used in a barometer, one would need along tube in order to measure the pressure. Using mercury, a shorter tube can be used.24. a. Boyle’s law – At constant temperature, pressure is inversely proportional to volume.1KP α V , to eliminate proportionality sign, V P , where K is theproportionality constant.b. Charles’ law – At constant pressure, temperature is directly proportional to volume.VV α T, to eliminate proportionality sign, V KT or K T , where K is theproportionality constant.c. Avogadro’s law – At constant temperature and pressure, the number of moles of gas isdirectly proportional to its volume.nn α V, to eliminate proportionality sign, n KV or K V , where K isthe proportionality constant.d. Dalton’s law of Partial Pressures – The total pressure of a mixture of gases is just the sumof the pressures each gas would exert if each werepresent alone.PT PA PB PC This also states that the total number of moles of gas A, gas B,and so on are directly proportional to the total pressure.ntotal RTPtotal V
25. Applying Boyle’s law, we can say that as the pressure decreases, the volume increases. Theballoon while rising in the air experiences a decrease in the pressure. So as the balloon isrising, pressure decreases and the volume of the balloon expands.26. At STP, meaning Standard Temperature and Pressure:T 273.15 KP 1 atm or 760 mmHg27. a. P1V1 P2V20.890 atm x 5.75 L 1.25 atm x V20.890 atm x 5.75 LV2 4.09 L1.25 atmb. P1V1 P2V20.890 atm x 5.75 L 0.350 atm x V20.890 atm x 5.75 LV2 14.6 L0.350 atm28. PV nRTatm L75 atm x V 1 mol x 0.0821 mol K x 1073.15 Katm L1 mol x 0.0821 mol K x 1073.15 KV 1.17 L75 atmPV0.20 atm x 1.00 x 10 4 L29. n RT 8.17 x 101 molatm L0.0821 mol K x 298.15 K2 mol BaO2169.3 g BaO28.17 x 101 mol O2 x 1 mol Ox 1 mol O 2.77 x 10 4 g BaO22230. a. 2NF3 3H2O NO 6HF NO21 mol NF31 mol NOb. at STP: 6.00 L NF3 x 24.4 L NF x 2 mol NF 0.123 mol NO331 mol H2O1 mol NO6.00 L H2O x 24.4 L H O x 3 mol H O 0.0820 mol NO22atm L0.0820 mol x 0.0821 mol K x 273.15V 1.84 L1 atmP1P231. T T12P1T21.82 atm x 1208 KP2 7.45 atmT1295 Katm L35.8 g x 0.0821 mol K x 319 Kwt(RT)32. P V(MM) 2.29 atmg12.8 L x 32.00 mol1 mol33. a. 42.1% C 42.1 g C x 12.01 g C 3.51 mol C1 mol H5.30% H 5.30 g H x 1.0089 g H 5.26 mol H
1 mol N24.6% N 24.6 g N x 14.01 g N 1.76 mol N100 – 72 28.0 g1 mol O28.0 g x 16.00 g O 1.75 mol Osimplest ratio:3.515.261.761.75 2 3 11.751.751.751.75 1empirical formula C2H3NOb. PV nRTgatm L(0.98 atm) (0.125 L) 0.229 MM x 0.0821 mol K x 372.15 K7.000.1225 MM0.1225 MM 7.007.00MM 0.1225gMM 57.1 molc. C2 2(12.01) 24.02H3 3(1.008) 3.024N
Methyl salicylate is a common active ingredient in liniments such as Ben-Gay. It is also known as oil of wintergreen. It is made up of carbon, hydrogen and oxygen atoms. When a sample of methyl salicylate weighing 5.287g is burned in excess oxygen, 12.24g of carbon dioxide and 2.505g of water are formed. What is the simplest formula for oil of wintergreen? For questions 13-18: Aspartame is an .
