CHEM 102 WINTER 16 PRACTICE FINAL EXAM (C) KEY,100% CORRECT

CHEM 102 WINTER 16 PRACTICE FINAL EXAM (C) KEY 1. What is true about cytosine? Choose ALL true statements. A. All of the nitrogen atoms are sp3 hybridized. B. The bond angle around all carbon atoms are around 120°. C. Cytosine can potentially make up to 8 hydrogen bonds. D. All of the carbon atoms are sp2 hybridized. E. There are a total of 3 pi bonds in this molecule. 2. Rank the following diatomic molecules/ions in terms of decreasing stability. Please choose a SINGLE answer. He2 O2+ CN- B 2- NF A. CN- > O2+ > B 2- = NF > He B. He2 > NF > B22- > O + > CN- C. CN- > O2+ > NF > B22- > He2 D. CN- > O2+ > B 2- > NF > He E. He2 > B 2- > NF > CN- > O 2- 3. Which of the following ions will likely have the shortest Cl–O bond length? Please choose a SINGLE answer. A. ClO- B. ClO2- C. ClO3- D. ClO4- E. Cannot be determined 4. A metal nitride has a nitrogen atom at each corner and a metal atom at each edge to make up a unit cell. Which is the empirical formula for this metal nitride? Please choose a SINGLE answer. A. Ba3N2 B. Na3N C. AlN D. Ti3N4 E. NaN3 5. Rank the following molecules in terms of increasing volatility. Please choose a SINGLE answer. I II III IV V C2H6 C3H8 A. II < V < III < IV < I B. I < IV < III < V < II C. II < IV < V < III < I D. II < V < III < I < IV E. III < I < V < IV < II 6. Solutions are made containing 0.5 moles of each of the following compounds below in 5.0L of H2O. Which compound will have a solution with the lowest boiling point? Please choose a SINGLE answer. A. KNO3 B. HCl C. S8 D. HNO3 E. Na3PO4 7. The following phase diagram for I2 is given. Given that the enthalpy of sublimation for I2 is 62.4 kJ/mol, and the enthalpy of fusion is 15.3 kJ/mol, what is the pressure of I2 at the triple point? Please choose a SINGLE answer. A. 9.7 atm B. 0.10 atm C. 1.0 atm D. 0.046 atm E. 4.8 x 10-9 atm 8. To treat a burn on your hand, you obtain 0.983 mol of ice that has an initial temperature of -13.1 °C. Assuming all of the ice melts, the water resulting from the melting ice reaches the temperature of your skin at of 29.5 °C. How much energy is absorbed by the ice and resulting liquid water? Assume all the remaining water stays in your hand. Please choose a SINGLE answer. Cp(ice) = 2.087 J g-1C-1 Cp(liquid H2O) = 4.184 J g-1C-1 ΔHfusion(H2O) = 6.01 kJ/mol A. 8.6 J B. 2.7 kJ C. 7.6 J D. 8.6 kJ E. 7.6 kJ 9. Given the two forms of carbon, choose ALL true statements. A. These structures are likely colorless in solution. B. The carbon atoms are sp2 hybridized. C. The two structures likely have different band gaps but are more conducting than diamond. D. Both structures likely have similar conductive properties to diamond. E. None of the above is true. 10. Which statement is likely NOT true? Please choose a SINGLE answer. A. DNA-modified nanoparticles can be used as programmable atoms to form 3D crystalline structures. B. Spherical nucleic acids (SNA) are formed by linking single-stranded oligonucleotides to gold nanoparticles through a (Au–S) bond. C. SNAs are not capable of binding to adjacent SNAs through hydrogen bonding interactions between the adjacent single-stranded oligonucleotides. D. Nanoscale materials can exhibit different properties from their larger bulk analogs. E. Nanoparticles can be imaged using electron microscopic techniques. 11. Use the polymer structure given to choose ALL true statements. A. This structure appears to be formed by vulcanization. B. This is the product of cross-linking polyisoprene units with S8. C. This structure is more rigid and durable than the material it was created from. D. This polymer is formed by condensation polymerization. E. This structure is a product of hybridization of two polymer units by hydrogen bonds. 12. You have two solutions: one solution of prism-shaped silver nanoparticles and one of spherical CdSe quantum dots, but forgot to label the vials. How could you differentiate the solutions in the lab? Choose ALL true statements. A. By measuring fluorescence. The CdSe quantum dots fluoresce while the Ag particles do not. B. X-ray diffraction would show differences in structure and ultimately composition. C. Conductivity of silver would increase with increasing temperature. D. Transmission electron microscopy will show differences in particle size and shape. E. They are indistinguishable because they are nanoscale materials. 13. Which of the following options yield correct unit cell structures given the nanoparticle (NP) diameter, DNA length and sequence? Please choose a SINGLE answer. I. Particle I: 10nm NP, 5nm DNA, 3’ ATATAT 5’ a. Particle II: 10nm NP, 5nm DNA, 3’ ATATAT 5’ b. Structure: FCC II. Particle I: 15nm NP, 5nm DNA, 3’ TAGCCA 5’ a. Particle II: 10nm NP, 10nm DNA, 3’ TGGCTA 5’ b. Structure: BCC-like III. Particle I: 10nm NP, 5nm DNA, 3’ ATGCGC 5’ a. Particle II: 10nm NP, 5nm DNA, 3’ CGACAT 5’ b. Structure: BCC-like IV. Particle I: 15nm NP, 5nm DNA, 3’ ATATAT 5’ a. Particle II: 15nm NP, 5nm DNA, 3’ TATATA 5’ b. Structure: No crystallization will occur A. I, II B. I only C. I, III, IV D. II only E. I, II, IV A or E accepted as a correct answer. 14. Given the following: I) N2O(g) + 1/2 O2(g) ⇌ 2NO(g) Kc = 1.7 × 10-13 II) N2 (g) + O2 (g) ⇌ 2NO(g) Kc = 4.1 × 10-31 Find the value of the equilibrium constant for the following equilibrium reaction: N2(g) + 1/2 O2(g) ⇌ N2O(g) Please choose a SINGLE answer. A. 7.0 × 10-44 B. 4.2 × 1017 C. 2.4 × 10-18 D. 1.6 × 10-9 E. 2.6 × 10-22 15. Which of the following statements about the respective equilibrium constants is INCORRECT? Please choose a SINGLE answer. A. K= 1.4 × 1083; reaction mixture is mostly comprised of products at equilibrium. B. K=1.6 × 10-23; reaction is highly unlikely to occur. C. K=1.8 × 10-5; equilibrium reaction has more reactants than products at equilibrium. D. K=1.0; equilibrium reaction has equal amounts of products and reactants. E. K=3.2 × 103; the reaction mixture has more reactants than products at equilibrium. 16. On the final day of class, Eberhard performed the thermite reaction, which required the use of a blowtorch to initiate the reaction. Given the reaction and information below, which of the following statements about this reaction are FALSE? Please choose a SINGLE answer. Fe2O3 (s) + 2 Al (s) → 2 Fe (s) + Al2O3 (s) ΔHº = –849 kJ ΔSº = –36.48 J/K I. The reaction is spontaneous at all temperatures. II. The reaction has a high activation energy. III. The reaction is enthalpically driven. IV. The reverse reaction could only become spontaneous at very low temperatures. A. III and IV B. II and III C. I and IV D. I, II, and III E. None of the above 17. For the decomposition of ammonium carbamate NH4(NH2CO2)(s) ⇌ 2NH3(g) + CO2(g) Kp = 0.0596 atm3 at a certain temperature. A solid sample of ammonium carbamate is introduced into an empty container, and at equilibrium some solid remains in the container. What is the partial pressure of NH3(g) in the container? Please choose a SINGLE answer. A. 0.492 atm B. 0.738 atm C. 0.246 atm D. 0.100 atm E. 0.924 atm 18. To make iron, a steel mill takes rust (Fe2O3) and reacts it with coke (a form of carbon) to make iron and CO2. This is a nonspontanenous reaction at room temperature, but becomes spontaneous at high temperature. Assuming enthalpy and entropy are constant at all temperatures, determine the temperature at which this reaction is spontaneous. (ΔH=465 kJ/mol; ΔS=552J/mol.K) Please choose a SINGLE answer. A. 842 K B. 0.842 K C. 1187 K D. 464 K E. 421 K 19. Consider the reaction: 3N2(g) + 2O3(g) → 6NO(g) ΔHf ° 0.00 142.26 90.37 kJ/mol ΔSf° 191.5 237.7 210.6 J/mol.K What is ΔG° for this reaction in kJ at 298 K? Please choose a SINGLE answer. A. 93 kJ B. 151 kJ C. 194 kJ D. -220 kJ E. 156 kJ 20. 5.0 mol chlorine and 3.0 mol bromine were placed in a 25.0 L container and kept at 300K until equilibrium was reached for the reaction: Br2(l) + Cl2(g) ⇌ 2BrCl(g) At the point of equilibrium there were 82.63 g of Cl2(g). Compute the value of Kp for this reaction. Please choose a SINGLE answer. A. 2.02 atm B. 0.05 atm C. 10.1 atm D. 49.7 atm E. 8.35 atm 21. At a temperature of 100K, the equilibrium constant (Kc) for a reaction is 0.08. The value of Kc is 5.0 when the temperature is raised to 400K. What is the enthalpy change ΔH for the reaction and how is the distribution of products and reactants affected at higher temperatures? Please choose a SINGLE answer. A. 4.58 kJ; More products are formed at the higher temperature B. -4.58 kJ; More reactants are formed at the higher temperature C. 4.58 J; More reactants are formed at the higher temperature D. -4.58 J ; More products are formed at the higher temperature E. 4.58 kJ; No side of the reaction is favored at the higher temperature 22. Which of the following actions will shift the reaction to favor product formation at equilibrium? Please choose a SINGLE answer. Ag2O(s) → 2Ag(s) + 1/2O2(g) ΔH° = +31.05 kJ/mol A. Decrease the volume of the container B. Increase the temperature C. Add 0.5 mol of Ag2O and 0.5 mol of Ag D. Add a catalyst E. Adding Ar(g) Constants and Equations: R = 8.3145 J mol−1 K−1 = 0.08206 L atm mol–1 K–1 Na = 6.022 x1023 molecules/atoms mol–1 1 atm = 760 Torr =760 mm Hg 0 C = 273 K PV = nRT ΠV = nRT ΔTf = –iKfm ΔTb = iKbm Ptot = xAP°A + xBP°A q = ΔH = mCpΔT Kp=Kc(RT)Δn Qp = Qc(RT) Δn ΔSuniv = ΔSsys + ΔSsurr ΔSsurr = -H/T G = H - TS G = G + RTlnQ ΔG° = –RTlnK Greaction = Gf(products) – Gf(reactants) ΔH°reaction = ΔΗ°f(products) – ΔH°f(reactants) ΔS°reaction = ΔS°(products) – ΔS°(reactants)