Topics in the June 2007 Exam Paper for CHEM1001

Transcription

1 June 007 Topics in the June 007 Exam Paper for CHEM1001 Click on the links for resources on each topic. 007-J-: 007-J-3: 007-J-4: 007-J-5: 007-J-6: 007-J-7: 007-J-8: 007-J-9: 007-J-10: Elements and Atoms Chemical Equations Stoichiometry Lewis Model of Bonding VSEPR Elements and Atoms Stoichiometry Chemical Equations Chemical Equations Stoichiometry Thermochemistry Chemical Equilibrium Introduction to Electrochemistry Electrochemistry First Law of Thermodynamics Electrolytic Cells Introduction to Electrochemistry Electrochemistry Batteries and Corrosion Chemical Equilibrium Gas Laws

2 /01(a) The University of Sydney FUNDAMENTALS OF CHEMISTRY 1A - CHEM1001 FIRST SEMESTER EXAMINATION CONFIDENTIAL JUNE 007 TIME ALLOWED: THREE HOURS GIVE THE FOLLOWING INFORMATION IN BLOCK LETTERS FAMILY NAME OTHER NAMES SID NUMBER TABLE NUMBER INSTRUCTIONS TO CANDIDATES All questions are to be attempted. There are 0 pages of examinable material. Complete the written section of the examination paper in INK. Read each question carefully. Report the appropriate answer and show all relevant working in the space provided. The total score for this paper is 100. The possible score per page is shown in the adjacent tables. Each new short answer question begins with a. Electronic calculators, including programmable calculators, may be used. Students are warned, however, that credit may not be given, even for a correct answer, where there is insufficient evidence of the working required to obtain the solution. Numerical values required for any question, standard electrode reduction potentials, a Periodic Table and some useful formulas may be found on the separate data sheet. Pages 17, 1 and 4 are for rough working only. OFFICIAL USE ONLY Multiple choice section Pages Max Gained Short answer section Page Max Gained Marker Total 60 Check Total

3 CHEM J- June 007 /01(a) Write balanced equations for the following nuclear reactions. 4 Naturally occurring thorium 3 undergoes alpha decay. A nuclide undergoes beta decay and produces caesium 133. A cook uses a microwave oven to heat up a meal. The wavelength of the radiation is 0.01 m. Calculate the frequency and energy of a photon of this radiation. Frequency: Energy: What mass of calcium chloride is required to make 50 ml of a 0.1 M solution? 3 What amount of chloride ions (in mol) is present in 30.0 ml of this solution?

4 CHEM J- 3 June 007 /01(a) Complete the following table. 9 Molecular formula SF 6 NH 3 Name chlorine trifluoride Lewis structure Number of bonding electron pairs on central atom Number of nonbonding electron pairs on central atom Molecular shape Silicon is essential to the computer industry as a major component of chips. It has three naturally occurring isotopes, the relative abundance of each being given below. Calculate the atomic mass of silicon. Isotope Mass of isotope (a.m.u.) Relative abundance 8 Si % 9 Si % 30 Si %

5 CHEM J- 4 June 007 /01(a) The complete combustion of butane, C 4 H 10, in air gives water and carbon dioxide as the products. Write a balanced equation for this reaction. 4 What mass of oxygen is required for the complete combustion of 454 g of butane and what masses of carbon dioxide and water are produced? During physical activity, lactic acid forms in the muscle tissue and is responsible for muscle soreness. Elemental analysis shows that it contains by mass 40.0% C, 6.71% H and 53.3% O. Determine the empirical formula of lactic acid. 4 Given that lactic acid has a molar mass of g mol 1, determine its molecular formula.

6 CHEM J- 5 June 007 /01(a) If 50 ml of a 0.10 M solution of AgNO 3 is mixed with 50 ml of a 0.40 M solution of Na CO 3, what mass of Ag CO 3 will precipitate from the reaction? 4 What is the final concentration of CO 3 ions in the solution after the above reaction? Give balanced ionic equations for the reactions that occur in each of the following cases. 3 Sodium metal is added to excess water. Solutions of cobalt(ii) nitrate and sodium phosphate are mixed. Solid calcium carbonate is dissolved in dilute nitric acid.

7 CHEM J- 6 June 007 /01(a) A 60.0 g piece of Ag metal is heated to 90.0 C and dropped into 10.0 g of water at 5.0 C in a well insulated container. The final temperature of the Ag-H O mixture is 6.7 C. Calculate the specific heat of silver. Data: The specific heat of water is 4.18 J g 1 K 1. 3 Determine K c for the reaction ½O (g) + Na O(s) Na O (s) at 5 C. Data: Na O(s) Na(s) + ½O (g) K c = 10 5 at 5 C. Na O (s) Na(s) + O (g) K c = at 5 C.

8 CHEM J- 7 June 007 /01(a) Consider a cell composed of the following half-reactions. Ag + (aq) + e Ag(s) Cr(s) Cr 3+ (aq) + 3e What is the balanced equation for the spontaneous reaction? What is the value of E for the cell? Relevant standard reduction potentials are on the data sheet. Calculate the standard heat of reaction for the following reaction. Data: Zn(s) + Cu + (aq) Cu(s) + Zn + (aq) o H f = kj mol 1 for Cu + (aq) o H f = 15.4 kj mol 1 for Zn + (aq)

9 CHEM J- 8 June 007 /01(a) An electrolytic cell contains a solution of MCl 3. A total charge of 3600 C is passed through the cell, depositing 0.65 g of the metal, M, at the cathode. What is the identity of the metal, M? 4 A metal-metal hydride battery has the following shorthand notation: MH(s), M(s) OH (aq) OH (aq) NiO(OH)(s), Ni(OH) (s) 3 Which component of the battery is the cathode? Give the balanced half equation of the reaction that takes place at the cathode. Why is it important that all redox active species are solids in this reaction?

10 CHEM J- 9 June 007 /01(a) K p = 7.0 for the reaction Br (g) + Cl (g) BrCl(g) at 400 K. Suppose a 1.0 L flask is filled with 0.30 atm Br (g) and 0.30 atm Cl (g) at 400 K. Find the pressures of all three gases at equilibrium. 4 p(br ): p(cl ): p(brcl): THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY

11 CHEM J- 10 June 007 /01(a) The Voyager I spacecraft determined that the atmospheric pressure at the surface of Saturn s moon, Titan, is 1.6 times that of earth and that the atmosphere contains 6.0 mol % methane, CH 4. What is the partial pressure of methane on Titan in mmhg? Many gases are available for use in compressed gas cylinders, in which they are stored at high pressures. Calculate the mass of O that can be stored at 0 C and 170 atm pressure in a cylinder with a volume of 60.0 L. 3 What volume would this mass of oxygen occupy at 1.00 atm pressure and 0 C?

12 /01(b) June 007 CHEM1001 FUNDAMENTALS OF CHEMISTRY 1A DATA SHEET Physical constants Avogadro constant, N A = mol 1 Faraday constant, F = C mol 1 Planck constant, h = J s Speed of light in vacuum, c = m s 1 Rydberg constant, E R = J Boltzmann constant, k B = J K 1 Permittivity of a vacuum, ε 0 = C J 1 m 1 Gas constant, R = J K 1 mol 1 = L atm K 1 mol 1 Charge of electron, e = C Mass of electron, m e = kg Mass of proton, m p = kg Mass of neutron, m n = kg Properties of matter Volume of 1 mole of ideal gas at 1 atm and 5 C = 4.5 L Volume of 1 mole of ideal gas at 1 atm and 0 C =.4 L Density of water at 98 K = g cm 3 Conversion factors 1 atm = 760 mmhg = kpa 1 Ci = Bq 0 C = 73 K 1 Hz = 1 s 1 1 L = 10 3 m 3 1 tonne = 10 3 kg 1 Å = m 1 W = 1 J s 1 1 ev = J Decimal fractions Decimal multiples Fraction Prefix Symbol Multiple Prefix Symbol 10 3 milli m 10 3 kilo k 10 6 micro µ 10 6 mega M 10 9 nano n 10 9 giga G 10 1 pico p

13 /01(b) June 007 CHEM1001 FUNDAMENTALS OF CHEMISTRY 1A Standard Reduction Potentials, E Reaction E / V Co 3+ (aq) + e Co + (aq) +1.8 Ce 4+ (aq) + e Ce 3+ (aq) +1.7 MnO 4 (aq) + 8H + (aq) + 5e Mn + (aq) + 4H O Au 3+ (aq) + 3e Au(s) Cl + e Cl (aq) O + 4H + (aq) + 4e H O +1.3 Pt + (aq) + e Pt(s) MnO (s) + 4H + (aq) + e Mn 3+ + H O Pd + (aq) + e Pd(s) +0.9 Ag + (aq) + e Ag(s) Fe 3+ (aq) + e Fe + (aq) Cu + (aq) + e Cu(s) Cu + (aq) + e Cu(s) Sn 4+ (aq) + e Sn + (aq) H + (aq) + e H (g) 0 (by definition) Fe 3+ (aq) + 3e Fe(s) 0.04 Pb + (aq) + e Pb(s) 0.13 Sn + (aq) + e Sn(s) 0.14 Ni + (aq) + e Ni(s) 0.4 Cd + (aq) + e Cd(s) 0.40 Fe + (aq) + e Fe(s) 0.44 Cr 3+ (aq) + 3e Cr(s) 0.74 Zn + (aq) + e Zn(s) 0.76 H O + e H (g) + OH (aq) 0.83 Cr + (aq) + e Cr(s) 0.89 Al 3+ (aq) + 3e Al(s) 1.68 Mg + (aq) + e Mg(s).36 Na + (aq) + e Na(s).71 Ca + (aq) + e Ca(s).87 Li + (aq) + e Li(s) 3.04

14 /01(b) June 007 CHEM1001 FUNDAMENTALS OF CHEMISTRY 1A Useful formulas Quantum Chemistry E = hν = hc/λ λ = h/mv 4.5k B T = hc/λ E = Z E R (1/n ) x (mv) h/4π q = 4πr T 4 Acids and Bases pk w = ph + poh = pk w = pk a + pk b = ph = pk a + log{[a ] / [HA]} Colligative properties π = crt P solution = X solvent P solvent p = kc T f = K f m T b = K b m Radioactivity t ½ = ln/λ A = λn ln(n 0 /N t ) = λt 14 C age = 8033 ln(a 0 /A t ) years Electrochemistry G = nfe Moles of e = It/F E = E (RT/nF).303 logq = E (RT/nF) lnq E = (RT/nF).303 logk = (RT/nF) lnk E = E logq (at 5 C) n Gas Laws PV = nrt (P + n a/v )(V nb) = nrt Kinetics t ½ = ln/k k = Ae Ea/RT ln[a] = ln[a] o kt k Ea ln = k R T T ( ) 1 1 Thermodynamics & Equilibrium G = H T S G = G + RT lnq G = RT lnk K p = K c (RT) n Miscellaneous I A = log10 I A = εcl 0 e E = A 4πε r 0 N A Mathematics If ax + bx + c = 0, then x = ln x =.303 log x ± a b b 4ac

15 PERIODIC TABLE OF THE ELEMENTS HYDROGEN H HELIUM He LITHIUM Li BERYLLIUM Be BORON B CARBON C NITROGEN N OXYGEN O FLUORINE F NEON Ne SODIUM Na.99 1 MAGNESIUM Mg ALUMINIUM Al SILICON Si PHOSPHORUS P SULFUR S CHLORINE Cl ARGON Ar POTASSIUM K CALCIUM Ca SCANDIUM Sc TITANIUM Ti VANADIUM V CHROMIUM Cr MANGANESE Mn IRON Fe COBALT Co NICKEL Ni COPPER Cu ZINC Zn GALLIUM Ga GERMANIUM Ge ARSENIC As SELENIUM Se BROMINE Br KRYPTON Kr RUBIDIUM Rb STRONTIUM Sr YTTRIUM Y ZIRCONIUM Zr NIOBIUM Nb MOLYBDENUM Mo TECHNETIUM Tc [98.91] 44 RUTHENIUM Ru RHODIUM Rh PALLADIUM Pd SILVER Ag CADMIUM Cd INDIUM In TIN Sn ANTIMONY Sb TELLURIUM Te IODINE I XENON Xe CAESIUM Cs BARIUM Ba HAFNIUM Hf TANTALUM Ta TUNGSTEN W RHENIUM Re OSMIUM Os IRIDIUM Ir PLATINUM Pt GOLD Au MERCURY Hg THALLIUM Tl LEAD Pb BISMUTH Bi POLONIUM Po [10.0] 85 ASTATINE At [10.0] 86 RADON Rn [.0] 87 FRANCIUM Fr [3.0] 88 RADIUM Ra [6.0] RUTHERFORDIUM Rf [61] 105 DUBNIUM Db [6] 106 SEABORGIUM Sg [66] 107 BOHRIUM Bh [6] 108 HASSIUM Hs [65] 109 MEITNERIUM Mt [66] 110 DARMSTADTIUM Ds [71] 111 ROENTGENIUM Rg [7] LANTHANIDES 57 LANTHANUM La CERIUM Ce PRASEODYMIUM Pr NEODYMIUM Nd PROMETHIUM Pm [144.9] 6 SAMARIUM Sm EUROPIUM Eu GADOLINIUM Gd TERBIUM Tb DYSPROSIUM Dy HOLMIUM Ho ERBIUM Er THULIUM Tm YTTERBIUM Yb LUTETIUM Lu ACTINIDES 89 ACTINIUM Ac [7.0] 90 THORIUM Th PROTACTINIUM Pa [31.0] 9 URANIUM U NEPTUNIUM Np [37.0] 94 PLUTONIUM Pu [39.1] 95 AMERICIUM Am [43.1] 96 CURIUM Cm [47.1] 97 BERKELLIUM Bk [47.1] 98 CALIFORNIUM Cf [5.1] 99 EINSTEINIUM Es [5.1] 100 FERMIUM Fm [57.1] 101 MENDELEVIUM Md [56.1] 10 NOBELIUM No [59.1] 103 LAWRENCIUM Lr [60.1] /01(b) CHEM1001 FUNDAMENTALS OF CHEMISTRY 1A June 007