CHM140Y-2008 - Student Name Student Number ~w~——_fl—...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Student Name: Student Number: ~w~——-*_fl—_ UNIVERSITY OF TORONTO MISSISSAUGA April 2008 Examination Course: CHM140Y5Y Instructor: Judith Poé Duration: 3 hours Aids allowed: Non-programmable Calculators Only You may be charged with an academic ofience for possessing the following items during the writing of an exam unless otherwise specified: any unauthorized aids, including but not limited to calculators, cellphones, pagers, wristwatch calculators, personal digital assistants (PDAs), iPODS, MP3 players, or any other device. 10’ any of these items are in your possession in the area of your desk, please turn them of and put them with your belongings at the front of the room before the examination begins. A penalty MAYBE imposed if any of these items are kept with you during the writing of your exam. Notes to Students: Enter your name and student number on each page of the examination paper before beginning the examination. Data for some questions is given at the bottom of this page. Answer 8 questions (out of 9). Each question counts for 20 marks. It is recommended that you spend about 20 minutes on each question. In the table below, circle the number of the question that you do not want to have marked. If you do not do that, we will only count the marks for the first 8 questions for which there is writing. We will not take the marks for the best 8 questions. Note that the question numbers and the page numbers are not the same, i.e. question 1 is on page number 2, question number 2 is on page number 3, etc. 1. /20 /20 0.0 l20 /20 /20 /20 l20 /20 “ I160 0 D l Atomic Masses (g/mol): H = 1.00, D a 2.00, N = 14.00, 0 = 16.00, C1": 35.45, Ag = 107.9 R = 0.08205 L atm/K mol 5 8.314 J/K mol F a 96,485 C/mol c = 3.0 X 108 m/s h= 6.63 2:1034 I s N 2 6.02 x 1023 atoms/Incl continued on page 2 [20] 1. a. Student Name: Student Number: 2 A 1.00 g sample of enriched water, a mixture of H20 and D20, reacted completely with C12 to give a mixture of HCl and DCl. The HCl and DCl were then dissolved in pure H20 to make a 1.00 L solution. A 25.00 mL sample of the 1.00 L solution was reacted with excess AgNO3 and 0.3800 g of an AgCl precipitate formed. What was the mass % of D20 in the original sample of enriched water? Equimolar samples of gaseous HCl and gaseous NH3 are introduced into the opposite ends of a long glass tube that is kept in a horizontal position. The gases diffuse across the tube and react spontaneously when they meet to produce a white ring in the tube. Where in the tube does the white ring form: closer to the HCI side of the tube, at the center of the tube, or closer to the NH3 side of the tube? Explain. Student Name: Student Number: 3 [20] 2. The chief constituent of lemon oil is a hydrocarbon, limonene, Whose W/w% composition is 88.16% C and 11.84% H. A solution of 8.362;; of limonene dissolved in 50.00g benzene (C6H6) boils at 83.2800. Pure benzene boils at 80.1SDC. The boiling point constant of benzene is 2.53 kg K/mol. Calculate the molecular formula and the molar mass of limonene. How many CC double bonds and/or rings do you think there are in the structure of limonene? Briefly explain. Student Name: Student Number: 4 [20] 3. 3. Describe an experiment that you could perform to Show that nitric acid, HNO3, is a strong acid but nitrous acid, HNOZ, is a weak acid. b. Draw the Lewis structures of the acids in a. and their anions. Explain, based on these structures, why you think that nitric acid is a stronger acid than nitrous acid. 0. Write a balanced redox reaction to show how nitrous acid reduces permanganate to Mn+2 in aqueous acid solution. Student Name: Student Number: 5 [20] 4. A 25.00 mi. sample of an unknown weak base, 0.1063M B, was titrated with a strong acid, 0.149SM HCl. When 10.00 mL of acid were added, the pH was 7.72. 1) Calculate the KB of the base. 2) Calculate the pH at the equivalence point of the titration. Use the simultaneous equations method for the calculations and be sure to explain any simplifying assumptions made in your calculations. 3) The pKB of NH3 is 4.74. Ifthe weak base in this titration was NH3, would the equivalence point of the titration be higher or lower than that with the unknown weak base? Explain. Student Name: [2015. a. Student Numb er: 6 For a second order reaction with a rate law, — d[A]/dt = 1{[A]2 , show that the time it takes for the [A] to fall to 1/4 of its initial value is three times longer than the time it takes for the [A] to fall to 1/2 its initial value. Beginning with the Arrhenius equation, k = PZe‘E‘“RT , derive an equation from which the rate constant for a reaction at one temperature could be calculated if the rate constant for that reaction at another temperature and the activation energy were known. Note any simplifications or assumptions made in the derivation. Student Name: Student Number: 7 [20] 6. a. “The entropy of vaporization, As“), of most liquids lies between 83 and 93 J/mol K. That generalization is known as Trouton’s Rule which is usually stated as follows: The entropy of vaporization of most liquids is 88 +/—5 J /mol K at the normal boilingpoini. " Calculate the entropy of vaporization of each of the compounds listed below and account for any deviations from Trouton’s Rule. Boiling Point (°C) AHW (kJ/mol) Asm (J/mol K) ——-- b. At what temperatures will each of the processes with the following values of enthalpy changes and entropy changes he spontaneous? Briefly explain any calculations. (1) AH = +20 k}, AS w +100 JK‘1 (2) AH = ~20 kl, AS = +10.0 J K"1 (3) AH = +20 M, AS = -10.0 JK‘1 (4) AH m —2() k], AS = —10.0 JK‘1 Student Name: Student Number: [20] 7. 3. Write the reactions to show how butan—Z-one can be synthesized from ethanol as the only source of carbon atoms and inorganic reagents. Label each step of the synthesis with its reaction type. b. Write the steps in the synthesis of trinitrobenzene from benzene, nitric acid and sulfuric acid. Explain Why a particular isomer is preferred. Student Name: Student Number: 9 [20] 8. a. Calculate the electrochemical potential generated by the following concentration cell at 25°C: - Ag(s) | AgNO3 (0.018M) ll AgNO3 (1.20M) | Agw . b. If a solution of NaCl is added to the 0.01 8M AgNO3 solution, will the cell voltage increase, decrease, or remain the same? Explain. 0. Given the following standard reduction potentials, calculate the KSP for AgClts). e“ (v) AgCl® + e" *+ Ag“) + C1"(aq, +0.22 Agflflq) + e0 —+ Agw +0.80 Student Name: Student Number: 10 I [20] 9. a. The ionization energy of gaseous Na atoms is 495.8 kJ/mol. What is the lowest possible frequency of light that can ionize a Na atom? b. Rutherford observed that some of the alpha particles directed at a thin gold foil were scattered back at angles greater than 90°. What did this suggest about the structure of the atom? c. How many electrons in an atom can have principle quantum number n=4? Explain. d. What is the meaning of the equation jg $2 dV = 1 ? e. Draw the Lewis structure of the compound methanaloxime, HZCNOH. Estimate the value of the bond angles for the HCH, the CNO, and the NOE bond angles. What hybrid orbitals are used by the C, N and O for their sigma bonds? ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern