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1 Chemistry 20, Section Final Exam, December 2, 20 Version 000 Instructions: Do not begin until 7:30 AM. The exam must be turned in by 9:20 AM. Be sure to mark the exam version number (000) on your scantron This exam should have 50 questions. Each question is worth 4 points for a total of 200 points. An information sheet and a periodic table are included on the next two pages. Use only a #2 Pencil to mark the best answer on the ScanTron Sheet. You will turn in only the Scantron sheet and the front cover page. You should keep the rest of the exam. Check blackboard for your exam score and final grade. Hopefully I will get this all done in the next 24 hours. I will be as merciful and fair as I can, following the guidelines outlined in the course syllabus. Have a restful and happy break. I hope to see you around campus and in other classes!! Bond D Bond D Bond D H H 436 C H 43 C C 348 C C 64 C C 839 C N 293 C N 65 C N 89 C O 358 C O 799 C O 072 C S 259 N H 39 N N 63 N N 48 N N 94 N O 20 N O 607 O H 463 O O 46 O S H 339 S S 266

2 2 Chemistry 20 Information Sheet Constants: Av. number = x 0 23 h = x 0-34 J s c = 3.00 x 0 8 m/s R H = 2.8 x 0-8 J R = L Atm/mole K Conversion factors: inch = 2.54 cm J = kg m 2 /s 2 T in kelvin = (temp in C) Hz = s - Atm = 0 kpa = 760 torr = 760 mm Hg Equations: d = m/v M V = M 2 V 2 H = H final -H initial specific heat q mass ΔT H rxn = Σ n H f (products) - Σ m H f (reactants) 2 = E k = mv E = q + w λυ = c E = hυ E = nhυ λ = h/mv 2 Z eff = Z S E = (-RH )( ) ΔE = (RH )( ) = hν 2 2 n ni n f n 2 H = D (bonds broken) - D (bonds formed) P V = nrt P = x P T Cg = k Pg Pa = Xa Pa Tf = kf m PV T Tb = kb m Formulas and names of common polyatomic ions: 2- Carbonate ion = CO 3 2- Sulfate ion = SO 4 - Nitrate ion = NO 3 - Perchlorate ion = ClO 4 3- Phosphate ion = PO 4 + Ammonium ion = NH 4 P2 V = T Common strong acids: HCl, HBr, HI, HClO 4, H 2 SO n Q k Q lattice energy = 2 d x = Pt = P + P2 + P n t s 2 2s 2 2p 6 3s 2 3p 6 3d 0 4s 2 4p 6 4d 0 4f 4 5s 2 5p 6 5d 0 5f 4 6s 2 6p 6 6d 0 6f 4

3 Periodic table here 3

4 4. Which of the following is an incorrectly stated relationship between two variables for an ideal gas? a. P b. P T c. V d. V T e. all the relations are correct V n 2. Autoclaves use pressurized steam (gaseous water) to obtain temperatures capable of killing microorganisms. The temperature required to kill microorganisms is 2 Celsius. Assuming water vapor (steam) behaves like an ideal gas, determine the pressure required for an autoclave with a volume of 50.0 liters and containing 3.0 moles of steam to reach 2 Celsius. a. 2.0 atm. b. 0. atm. c..29 atm. d. 92 atm. e atm. 3. A simple way to prepare oxygen in the laboratory is by the decomposition of potassium chlorate, which occurs upon heating: 2KClO 3 (s) 3O 2 (g) + 2KCl(s) Assuming the reaction goes to completion, if 0.0 grams of KClO3 are decomposed according to the balanced chemical equations shown above, what volume of O 2 will be produced at a pressure of.00 atmosphere and a temperature of 25.0 C? a liters b liters c liters d..33 liters e. 490 liters 4. You have a 5.00 liter vessel that contains 2.00 g CO 2, 3.00 g He, and 4.00 g N 2 at 42 C. What is the total pressure in the vessel in atmospheres? a atm. b. 38 atm. c atm. d. 2 atm. e. 6.2 atm. 5. Referring to the previous problem, what is the mol fraction of He in this gas mixture? a b c d e

5 5 6. Helium balloons are used as instruments for weather forecasting. You have a weather balloon with a volume of 5.00 x 0 3 liters which is launched when the temperature is 22.5 C and atmospheric pressure is 684 torr. At its final altitude, the atmospheric pressure is 55.0 torr and the volume of the balloon has expanded to 4.50 x 0 4 liters. What is the temperature at this altitude in degrees celsius? a C b C c C d. 6.3 C e C 7. Of the following processes, which are endothermic? (i) sublimation (ii) freezing (iii) condensation (iv) melting (v) deposition (vi) vaporization a. (ii), (iv), and (vi) b. (i), (iii), and (v) c. (i), (iv), and (vi) d. (ii), (iii). and (v) e. (i), (ii), and (v) 8. Examine the heating curve at the right. Which letters correspond to heating the liquid? a. A b. B c. C d. D e. E T A B C heat D E 9. Match the arrows with the correct phase equilibria: solid-liquid liquid-gas solid-gas (a) (ii) (iii) (i) (b) (i) (iii) (ii) (c) (i) (ii) (iii) (d) (iii) (ii) (i) (e) (ii) (i) (iii) P (i (ii (iii) 0. Dipole-dipole attractions are seen in interactions between: a. an ion and a permanant dipole b. neutral nonpolar molecules c. any two polar molecules d. molecules where H interacts with N, O, or F e. polar molecule and a nonpolar molecule T

6 6. Which of the following cannot use hydrogen bonding as an intermolecular attractive force in a liquid solution of the molecule? O O O NH 3 H 2 O H C CH 3 H 3 C O CH 3 H 3 C i ii iii iv v vi a. they all can use hydrogen bonding b. iii, iv, and vi c. iv and vi d. iv, v, and vi e. iii, iv, v, and vi C O H H C H 2. Given the following information: specific heat of solid water (ice) = 2.09 J/(g C), specific heat of liquid water = 4.8 J/(g C), specific heat of water vapor =.84 J/(g C), enthalpy of fusion of water is 6.00 kj/mol, enthalpy of vaporization of water is kj/mol. You take several ice cubes with a combined mass of 50.0 grams out of your freezer where they are at a temperature of -5 C and let them melt until they reach room temperature, which is 25 C. What was the heat change associated with this process? a. 6.8 kj b. 6.8 x 0 3 kj c..5 x 0 3 kj d kj e x 0 3 kj 3. For a collection of molecules or ions of relatively constant size, rank the following intermolecular attractive forces from WEAKEST ( st ) to STRONGEST (last) a. London dispersion, dipole-dipole, hydrogen bond, ion-dipole b. London dispersion, dipole-dipole, ion-dipole, hydrogen bond c. dipole-dipole, London dispersion, ion-dipole, hydrogen bond d. dipole-dipole, London dispersion, hydrogen bond, ion-dipole e. dipole-dipole, ion-dipole, hydrogen bond, London dispersion 4. Which of the following molecules cannot use dipole-dipole attractions as an intermolecular attractive force? (i) AsI 3 (ii) SF 4 (iii) H 2 Se (iv) BF 3 a. (iv) only b. (ii) and (iv) c. (ii) and (iii) d. (i) and (iii) e. (ii), (iii), and (iv) 5. Which one of the following compounds will have the lowest boiling point? (a) CBr 4 (b) CF 4 (c) CI 4 (d) CCl 4

7 7 6. Which of the following elements would you predict to form a covalent network solid when solified from its standard state form? a. Ni b. C c. N d. O e. all of (b), (c) and (d) 7. Which is the best definition of boiling point? a. the temperature at which molecules have sufficient kinetic energy to escape from the liquid to gas state. b. the temperature where the vapor pressure of a liquid becomes equal to the external pressure. c. the temperature at which gas bubbles form within in a liquid d. the temperature required to break the intermolecular attractions between molecules in the liquid. e. these are all correct definitions of boiling point. 8. During the solution process, disruption of solute-solute interactions (i), disruption of solvent-solvent interactions (ii), and formation of solute-solvent interactions (iii). (i) (ii) (iii) (a) releases energy releases energy requires energy (b) requires energy releases energy requires energy (c) releases energy requires energy releases energy (d) requires energy requires energy releases energy (e) requires energy releases energy releases energy 9. The addition of a solute to water will result in freezing point (i), boiling point (ii), and vapor pressure (iii). a. (i) depression (ii) depression (iii) elevation b. (i) depression (ii) elevation (iii) elevation c. (i) depression (ii) elevation (iii) depression d. (i) elevation (ii) depression (iii) depression e. (i) elevation (ii) depression (iii) elevation 20. What is the dissolved concentration of O 2 in a lake at a depth of 33 feet where the pressure is 2.00 atm and the temperature is 20 degrees Celsius? The Henry s law constant for O 2 is.30 x 0-3 M/atm and the mol fraction of O 2 in air is 0.2. a. 5.5 x 0-4 M b. 2.7 x 0-4 M c..2 x 0-2 M d. 3. x 0-3 M e. 6.2 x 0-3 M

8 8 2. What is the boiling point at sea level ( atm. pressure) of a solution prepared by dissolving 40.0 g of NaCl in g of water? K b for H 2 O is 0.50 C/m. a C b C c. 0.4 C d C e C 22. Calculate the vapor pressure in a sealed flask containing 30.0 g of glucose, C 6 H 2 O 6, dissolved in 00.0 g of water at 25.0 C. The vapor pressure of pure water at 25.0 C is 23.8 torr. (a) 79.3 torr (b) 7.4 torr (c) torr (d) 23. torr (e) 24.5 torr 23. Which of the following solutions will have the lowest freezing point? a. 2.0 M glucose (C 6 H 2 O 6 ) b..5 M NaCl c..25 M CaCl 2 d..00 M AlCl 3 e. 3.0 M NH You have a separatory funnel containing water and carbon tetrachloride, which are immiscible. Predict which phases the following compounds would dissolve in within the separatory funnel (i) I 2 (ii) C 6 H 4 (iii) CuSO 4 (iv) NH 3 Water phase CCl 4 phase (a) CuSO 4, NH 3, I 2, C 6 H 4, (b) CuSO 4, NH 3, I 2 C 6 H 4, (c) CuSO 4, NH 3, C 6 H 4 I 2 (d) I 2, C 6 H 4, NH 3 CuSO 4 (e) I 2, C 6 H 4, CuSO 4, NH 3, 25. Which of the following is a correct definition of osmosis? a. Movement of solute across a semi-permeable membrane from the side with lower solute concentration to the side with higher solute concentration b. Movement of solute across a semi-permeable membrane from the side with higher solute concentration to the side with lower solute concentration c. Movement of solvent across a semi-permeable membrane from the side with lower solute concentration to the side with higher solute concentration d. Movement of solvent across a semi-permeable membrane from the side with higher solute concentration to the side with lower solute concentration e. absorption of chemical information by sleeping with your head resting on your textbook.

9 9 Comprehensive Section: Midterms -3 Material 26. Consider the following processes: (i) freezing of liquid water (ii) combustion of a hydrocarbon (iii) rusting of iron (iv) explosive decomposition of sodium azide to inflate an automobile airbag (v) evaporation of diethyl ether Which of these processes are correctly referred to as a chemical change? a. (i), (iii) and (v) b. (i) and (v) c. (ii), (iii) and (iv) d. (ii), (iii), (iv), and (v) e. (i), (ii), and (v) mg/cm 3 equals μg/m 3. a..00 x 0 9 b..00 x 0 2 c..00 x 0 7 d..00 x 0 6 e..00 x An element in the periodic table gains three electrons, which results in an ion with 36 electrons. The element also has 42 neutrons. What is the correct symbol for this ion? a. 75 Y 3- b. 75 Y 3+ c. 78 As 3- d. 78 Y 3+ e. 75 As For the combustion of the hydrocarbon hexane (C 6 H 4 ) in air, what is the coefficient in front of H 2 O when the chemical equation for the reaction is properly balanced? a. 6 b. 7 c. 2 d. 4 e What is the empirical formula of a compound that contains 62.0% C, 0.4% H, and 27.6% O by mass a. CH 2 O b. C 3 H 6 O 2 c. CH 4 O d. C 3 H 4 O e. C 3 H 6 O

10 0 3. If you dissolve 0.30 moles of ammonium nitrate in 0.70 liters of solution, what is the total concentration, in moles/liter, of all of the ions present in solution? a M ions b M ions c. 0.2 M ions d M ions e M ions 32. A solution was prepared by placing g of sucrose, C 2 H 22 O, in a flask and adding water to make a final volume of 0.25 L of solution. The concentration of sucrose in the solution is a M b. 7.8 M c. 0.3 M d. 44 M e M 33. Which is the correct balanced complete ionic equation for the reaction of the insoluble metal hydroxide milk of magnesia, Mg(OH) 2, with hydrochloric acid in your stomach. a. Mg(OH) 2(s) + 2 H + (aq) + 2 Cl - (aq) 2 H 2 O (l) + Mg 2+ (aq) + 2Cl - (aq) b. Mg(OH) 2(s) + 2 HCl (aq) 2 H 2 O (l) + MgCl 2(aq) c. d. Mg 2+ (aq) + 2 OH - (aq) + 2 H + (aq) + 2 Cl - (aq) Mg(OH) 2(s) + 2H + (aq) 2 H 2 O (l) + Mg Cl - (aq) 2 H 2 O (l) + Mg 2+ (aq) e. 2 OH - (aq) + 2 H + (aq) 2 H 2 O (l) 34. Consider the following compounds, all of which are soluble in water: I II III IV V Glucose, hydrochloric acid, Glycerol, Acetic acid, Ammonium C 6 H 2 O 6 HCl C 3 H 8 O 3 HC 2 H 3 O 2 carbonate, (NH 4 ) 2 CO 3 Which of these compounds would you expect to behave as strong electrolyte(s) in solution? a. I and IV only b. I, III, and IV only c. II and IV only d. II and V only e. II, IV, and V only 35. Under standard conditions, the reaction of 0.0 mol of H 2 with excess N 2 produces 308 kj of heat. Use this information to determine the enthalpy change associated with the following reaction, as written, in units of kj/mol. 3H 2 (g) + N 2 (g) 2NH 3 (g) ΔH =? kj/mol reaction a. 205 kj/mol b x 0 3 kj/mol c kj/mol d kj/mol e kj/mol

11 36. A chemical reaction that releases heat to the surroundings is said to be (i) and has a (ii) value of ΔH, while a chemical reaction that removes heat from the surroundings is said to be (iii) and has a (iv) value of ΔH (i) (ii) (iii) (iv) a. endothermic positive exothermic negative b. exothermic negative endothermic positive c. exothermic positive endothermic negative d. endothermic negative exothermic Positive e. endothermic negative exothermic negative 37. Of the following, which are correctly referred to as state functions? (i) the heat change for a chemical reaction carried out at constant pressure (ii) straight line distance from Salt Lake City to Logan (iii) amount of work performed in the combustion of a gallon of gasoline (iv) calories burned in a 20 minute workout (v) number of students currently in this room a. all of the above are state functions b. (i), (ii) and (v) only c. (ii) and (v) only d. (i), (iii), and (iv) only e. (ii), (iii), (iv), and (v) only 38. Given the data below, determine ΔH for the reaction: C (s) + 2H 2(g) CH 4(g) C (s) + O 2(g) CO 2(g) ΔH = kj H 2(g) + ½ O 2(g) H 2 O (l) ΔH = kj CH 4(g) + 2O 2(g) CO 2(g) + 2H 2 O (l) ΔH = kj a. -2 kj/mol b kj/mol c kj/mol d kj/mol e kj/mol 39. A banana contains about 290. kj of energy. Visible light was used as the source of energy in photosynthesis to make that banana. How many photons of visible red light with a frequency of 4.29 x 0 4 Hz would provide 290. kj of energy? a x 0 44 photons b..2 x 0 6 photons c..3 x 0 38 photons d x 0 8 photons e..02 x 0 24 photons 40. For the 4d yz orbital, the "d" specifies the orbital s: a. size b. shape c. orientation in space d. electron spin e. energy state

12 2 4. How much energy is required to excite an electron in a hydrogen atom from n = 3 to n = 7? a..98 x 0-9 J b. 4.5 x 0-9 J c x 0-9 J d x 0-20 J e. 3. x 0-9 J 42. How many electrons can occupy the (i) n = 2, (ii) n = 3 and (iii) n = 4 shells? (i) (ii) (iii) a b c d e Referring to the following bonds, which order is correct for increasing polarity (least polar first)? Si-F Si-Cl S-Cl P-Cl a. Si-F < Si-Cl < P-Cl < S-Cl b. S-Cl < P-Cl < Si-Cl < Si-F c. P-Cl < S-Cl < Si-Cl < Si-F d. S-Cl < P-Cl < Si-F < Si-Cl e. Si-F < P-Cl < Si-Cl < S-Cl 44. Which of the following possible Lewis structures for the cyanate ion (CNO - ) is both a correct structure AND the best structure based on formal charge considerations. (a) O C N (b) O C N (c) O C N (d) O C N 45. What is the oxidation number on the S atom in sulfurous acid, H 2 SO 3? a. +4 b. +6 c. +8 d. 0 e. -4

13 3 46. Valence shell electron pair repulsion (VSEPR) theory is based on the idea that a. atoms in molecules are restricted to 4 bonds, or 8 total electrons around each atom. b. Electron pairs about an atom arrange themselves in such a fashion as to maximize the interaction between each pair. c. nonbonded (lone) electron pairs require less space than bonded electron pairs. d. Electron pairs arrange themselves in such a fashion as to minimize the interaction between each electron pair. e. both (c) and (d) are correct 47. In the Lewis structure for IBr 4 -, I has (i) lone pairs of electrons and (ii) bonded pairs of electrons. a. 0, 4 b., 4 c. 2, 4 d. 4, 8 e. 4, 48. Using the information in the table of average bond energies on Page of this exam, estimate ΔH (in kj/mol reaction) for the combustion of BUTANE (be careful to use the right bond energy values and numbers of bonds, and look carefully at the reaction stoichiometry!): a kj b kj c. -0,435 kj d kj e.,696 kj 49. Which one of the following molecules would you predict to be polar? a. ICl 4 - b. CCl 4 c. SF 4 d. BH 3 e. CO What hybrid orbital set would be used for the central atom of a molecule that has a see saw molecular geometry? a. sp b. sp 2 c. sp 3 d. sp 3 d e. sp 3 d 2

Chemistry 1210, Section 1 Second Hour Exam October 26, 2011

Chemistry 1210, Section 1 Second Hour Exam October 26, 2011 Instructions: Do not begin until 8:30 AM. The exam must be turned in by 9:20 AM. This exam should have 25 questions. Each question is worth 4